Sebastian Francis said:
Remember the old days of AD&D, when it took months (of GAME time) to go up in level?
Nope. Didn't happen back then to me. As I recall, advancement could get very quick. We were young, however!
Here's a pertinent quote from Gary Gygax on the subject, back from TSR #7 (April 1976 - before AD&D!)
"When it is difficult to survive, a long process to gain levels, when there are many desired items of magical nature to seek for, then a campaign is interesting and challenging. Think about how much fun it is to have something handed to you on a silver platter — nice once in a while but unappreciated when it becomes common occurrence. This analogy applies to experience and treasure in the D & D campaign.
"It requires no careful study to determine that D & D is aimed at progression which is geared to the approach noted above. There are no monsters to challenge the capabilities of 30th level lords, 40th level patriarchs, and so on. Now I know of the games played at CalTech where the rules have been expanded and changed to reflect incredibly high levels, comic book characters and spells, and so on. Okay. Different strokes for different folks, but that is not D & D. While D & D is pretty flexible, that sort of thing stretches it too far, and the boys out there are playing something entirely different — perhaps their own name “Dungeons & Beavers,” tells it best. It is reasonable to calculate that if a fair player takes part in 50 to 75
games in the course of a year he should acquire sufficient experience points to make him about 9th to 11th level, assuming that he manages to survive all that play. The acquisition of successively higher levels will be proportionate to enhanced power and the number of experience points necessary to attain them, so another year of play will by no means mean a doubling of levels but rather the addition of perhaps two or three levels. Using this gauge, it should take four or five years to see 20th level. As BLACKMOOR is the only campaign with a life of five years, and GREYHAWK with a life of four is the second longest running campaign, the most able adventurers should not yet have attained 20th level except in the two named campaigns. To my certain knowledge no player in either BLACKMOOR or GREYHAWK has risen above 14th level."
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There's something of an assumption for regular play of D&D (and AD&D) in the "old days" that it would be about 6 sessions per level; that's a bit more explicitly stated in the Companion rules of Basic D&D rather than at any point in AD&D.
This would significantly slow after "name" level; so about 10th or so. One of the big changes of 3e is to make those high levels achievable by players (and, indeed, fun - the gap between MUs and Ftrs in 1e was wide).
Cheers!