I'd expect that most games would try to err more towards 40 minutes due to the 20 minute minimum and the rules require a minimum of 20 minutes. (my game can be speedrunned in about 5 minutes if you skip all dialogue and content, but is currently set up to require about 40-90 minutes of proper gameplay to finish. The problem is that speedruns can drastically shorten a game's length, which is especially bad in story focused games and lore focused games like mine.
What I've learned from the past is that fan favorites will be heavily determined by existing fanbases. The bigger your existing fanbases, the more call to action you can pull.