Seems I'm always hearing people describe the rule books of whatever edition they're playing in terms of their page count and size - usually saying something like "a DM has to memorize more than a hundred pages of material . . ."
I'm not sure where that comes from. Sure, it's helpful to memorize content, as I said in my book, because it saves time and encourages confidence. But most of the rules content does not have to be precisely memorized because it is there in the book when we need it.
Now, sorry, I don't have a copy of the 5e rule book and I'm never likely to own one. I do have a 3e copy of the Player's Handbook and DMG around somewhere, given to me by a quitting player, but they're in boxes and I don't care to look. Besides, it's the original Dungeon Masters Guide from 1e that gets all the criticism, because the organization is supposedly poor and it is so darn much to grok for the poor DM. So I'm going to discuss the book on my desk.
I don't use this book much for play anymore. Most of the rules that I use have been moved onto the wiki or duo-tangs full of spell rewrites that haven't made it onto the wiki yet. I only use the DMG for the occasional magic item description or the hirelings pages - I don't think I actually picked up the book at all last Saturday. This is therefore going to be sort of nostalgic to me.
The DMG is 240 pages. That sounds like a lot. It isn't, because most of it is not needed to run the game - even back in the day when the DMG was my principle go-to volume for every rule and table not found in the Player's Handbook. I'll try to explain.
Subtract the first 6 pages for the title page and index. That's followed by 4 pages of introduction that, while reading it is helpful, none of that is actually necessary to play the game. I mean, once you've read Gygax's preface, it's not like you're going to read it again before building your next dungeon or that you need to memorize what's said in order to answer questions. It's just fluff, as is the introduction, which only tells you a few philosophical things that apply to the game. You may suffer a bit for not having read this but it's not like this is a critical part of the rules.
Page 11 is another suggestion page on methods to roll dice to make a character. Once you make up your mind about this, the page is completely disposable. Then we have 2 pages that have a few useful tables - secondary skills, age and chance of contracting disease.
There's a bunch of writing on these pages but after the first initial read, none of has much importance. I went to these pages for two decades, every time I helped a player make a character, and I never felt any need to review the few comments or explanations for the tables. I knew what the tables meant - and if I memorized them, it was through repeated use. For example, I remember that a human mage would be 24 +2d8 years of age. If I needed to look, it took a second to find these two pages because the binding was cracked there.
The next page is disease, which I only needed if a character got one (I didn't roll for disease all the time, so this was very rare) and after that are a bunch of unnecessary comments about death, determination of maximum age, character abilities and character races. I've never had a character die of old age or even come close - and once I read through the description of abilities and races, I never had to look at that again.
Now we have 2 pages for name-level followers; 3 pages about the paladin's warhorse, assassin's spying, the nuance of thief abilities, setting traps, assassination experience points and the use of poison. All of it sort of interesting but most of it useless for everyday campaigning. If I needed those details, the content was there but for the most part I never went to these pages. Maybe once in a year of running. Once the rule is sorted about about poison with the player the player will remember every nuance and there just isn't any reason to look up this rule a second time.
Most of the book is like this. Page 21 is "the monster as a player character" and that certainly doesn't need to be read again. Then we get a whole page on lycanthropy (which I used once in 20 years of play) and 2 pages on alignment (which I never, ever used).
So here we are, page 24 and so far there are 2 pages I used regularly - and just for the tables there.
The whole book is like this. I used the gem and jewelry tables from page 25 & 26, quite a lot, but the reputed magical properties of gems was wasted space. I would have preferred more content on the values of other rare commodities (something that massively affected my desire for deeper trade tables). Still, these pages got used a lot. But they're followed by a page on armor (that is fairly useless) before getting to something that mattered: hirelings.
Now, again, pages 28 to 35 were damn useful. But none of it had to be 'memorized' - it could be looked up during a game while the characters were discussing who to hire. It was always an issue only when the players were relaxed and in town; it certainly wasn't something that troubled me during a high-tension game moment. Much of it did greatly affect my campaign - particularly things like obtaining henchmen. The information, however, was a boon, not a troublesome burden. Hell, we would have liked more useful stuff like this.
Instead we got a set of piss-poor rules about loyalty of hirelings (1 page), time in the campaign (1 page), notes about character spells (3 pages), a breakdown of too short, unsatisfactory side notes on spellcasting that should have been in the Player's Handbook (11 and a half pages). I think that Gygax and crew simply screwed up and realized there were details they'd overlooked and felt they could pass off as "important for the DM," justifying placement in the DMG because it was too late to fuck with the page count of the PH. All together, this is 16+ pages that were never looked at once the information was either discarded or simply standard in the campaign. In writing out spells for my wiki, I don't even address these pages - because the content is either obvious or completely wrong for my campaign (that is, the way I see spells working).
Page 47 starts a very disappointing 14 pages on half-done rules regarding movement in the outdoors, encounters, waterborne/underwater and air adventures, combat rules for each (where we haven't even reached combat in the book), invisibility, infravision, getting lost, forced movement, evasion, the known planes of existence, detection of evil and listening at doors. The sheer number of things covered in these 14 pages shows how completely useless these things were for any of the subjects discussed - so that here we have a black hole in the rule book. All I remember about this section was that if I wanted to run a shipboard adventure, I would go here and be incredibly disappointed at how frikkin' useless the rules here were.
Is the reader getting the idea yet? Most of the DMG is either useless or profoundly specific, applicable only in 1 session in 100 (in which case it probably wouldn't answer the game question and I'd have to house rule the situation anyway). There are 15 pages on combat, but again this is mostly very specific stuff that is easy to remember once the superfluous writing is ditched. We all read the example of melee several times but it's dispensable once the DM has run a few combats. Not that it isn't useful to read - it's only that where we're talking about the page count in terms of running the game, very little of this is needed. The combat tables are necessary - but THAC0 quickly eliminated any need for those. Of all the combat rules here, there are maybe 5 other pages that are actually relevant: surprise, the grenade page, turning undead, pummelling and grappling. Call it 7 in all.
In 75 pages, I've described 15 pages that I used virtually every session. From this point on in the book it gets worse. There's the saving throw pages from 79 to 81, the experience point reward table on 85 and then nothing immediately necessary until page 102 (height and weight). Now, this isn't to say that I didn't use a lot of that material about campaigns - but if we're talking about rules that needed to be memorized, none of it does. It's all back story and example, or something highly situational like intoxication or insanity that can be looked up if that ever happens. The same goes for the next section on mining, construction, siege weapon attacks and conducting the game - 10 pages. Then it's 3 pages of other games by TSR, followed by 6 totally useless and poorly thought out pages of magic research rules (which translate as "spend way, way more money than the magic item is worth if you want to make one").
This brings us to a spectacular 51 pages of magic items. This is way past memorizing and frankly I've never (in 36 years of play) read every page. Hell, why bother? At first I used to think I didn't want to know what all the magic was in case I came across it while playing but now it's just that reading through all this magic would be horrifically boring.
I do still use this part of the book - mainly because I can't be bothered to copy it all into the wiki. It's there when I need to look something up. It certainly isn't critical to the gaming process.
Sigh. I'm going to stop this. The reader should be getting the point by now. I'm up to using 16 pages out of 169, less than 10% of the book to this point. All that follows are the appendices, a lot of encounter tables I used a lot (but didn't need to memorize), generation tables I used a lot (endlessly disappointed by them), a long list of monsters rehashed from the Monster Manual (20 pages), some sad gambling rules, some interesting things on traps, dungeon dressing and herbs (which I would have loved seen expanded and given precise effects gamewise), a bit of stuff on encumbrance and some NPC magic generation tables I used to use before cutting back on my game's magic availability.
None of this was game-predominant.
238 pages of rules? Horseshit. 25 pages of pertinent data jammed between 200+ pages of ideas, inspiration, accounting, accessible data and pure, unmitigated crap.
More than enough, however, to make me rethink virtually every aspect of running a game and improving it, filling in all the gaps the rulebook didn't fill with entire libraries of properly done research on medieval culture and trade, adding rules from every other game I had access to and always thinking, thinking, on how the process could be redesigned and invigorated.
Damn, I wish the DMG had been a thousand pages. It might then have approached the tool I needed.