Special Note Regarding Fighters' Progression: This table is designed to allow fighters to advance by 5% per level of experience attained, rather than 10% every 2 levels, if you believe that such will be helpful in your particular campaign. If you opt for a per level advancement in combat ability, simply use the table but give a +1 "to hit" bonus to fighters who attain the second level of experience shown in each group of 2 levels, i.e. 1-2, 3-4, etc. You may, of course, elect not to allow per level combat advancement. [DMG p. 74]I bring this up partly because some people overlook it, and partly because it provides credence for Gygax being amenable towards combat charts with a "smooth" progression in them. In fact, we might hypothesize that the small, "jumpy" charts we see in the classic game are merely a concession to the limited page space available in OD&D and AD&D. A mechanic where we check d20 + level + AC ≥ 21 would perform the task identically, without any need for table lookups (i.e., one pip difference from what I call "Target 20"). This idea is further expanded upon in a Dragon Magazine article by Len Lakofka titled "New charts, using the '5% principle'", which begins thus:
© 1983 E. Gary Gygax & Lenard LakofkaThereafter, consolidated charts are presented for attacks and saving throws which increment by exactly 5% (1 in 20) any time an improvement is made -- interpolating the existing tables in the AD&D DMG. This gives at least the impression of Gygax approval, due to (1) the conspicuous copyright notice, (2) the Gygax attribution, and (3) the distinction from the experience tables at the end of the article. I present the former tables below.
The following material is not official, but is provided for your study and comment. Gary Gygax has said that an expanded combat results table is certainly desirable, so perhaps that part of the following information will eventually be made part of the official rules. However, the suggestions on how to change the experience-point chart are entirely of my own devising. [Dragon #80, December 1983, p. 48]
Would I want to use these tables? Actually, no -- I think they've become too complicated visually. Once you have more than 7 categories per axis, a person's speed at cross-referencing is sure to fall off. The attacks table here is exacerbated by 6 different lines of numbers across the x-axis (the classes) that you need to distinguish between on a case-by-case basis.
What I really want to argue is that the fundamental intent behind these tables would, in fact, be better served by a simple, much shorter, numerical core rule, but for some reason the Gygax/Lakofka team lacked the mechanical creativity to invest the game with such. While it's been argued that tables can present complicated mechanics in an easy-to-reference fashion, the fact is, there's nothing complicated here for the tables to simplify -- the presented progressions are all inherently linear, and tablature may in fact be about the clunkiest way to express the desired, smooth system seeking a "5% principle".