Holmes's D&D excerpt: progress

"As a guideline, it should take a group of players from 6 to 12 adventures before any of their characters are able to gain sufficient experience to attain second level. This guidelining will hold true for successive levels. Note that it is assumed that the 6 to 12 adventures are ones in which a fair amount of treasure was brought back - some 10% to 20% of adventures will likely prove relatively profitless for one reason or another" (page 22 of Dr. Holmes's D&D)

There would have been rioting at my table if we progressed at that speed. 6 to 12 adventures is a miraculous number for a first level character to even survive in a world where you can start out with 1 HP and never more than 11.

"Adventure" is not defined though, so I don't know if those are excursions into the same dungeon, retreating when your arms are full or your comrades have fallen. In my head, "adventure" means session, but perhaps that's wrong.