TwoSix
"Diegetics", by L. Ron Gygax
We didn't dungeon crawl from room to room, but my last campaign did go from level 9 to level 13 in about two weeks of in-game time.Yes probably. I really cannot properly imagine the sort of game where there wasn't significant downtime and the characters didn't plan what they're going to do next. But I guess a lot of official modules are just dungeons where the characters kill monsters in rooms and go from level one to ten in two weeks of in-game time or something bizarre like that. I have never played that way though. (Sorry if the characterisation was inaccurate or unfair, but this was the only scenario where I can imagine increasing the number of spells you have access to by tenfold wouldn't be a massive game chancer.)