10-20 personally for the vast majority of games. However for dungeon crawlers I don't mind if they reach hundreds because I start those games with a "this is going to be a constant grind, repetitive enemies, advancing a little and backtracking a lot, one bad step and whole party is wiped and have to start from scratch" mentality. For other games I start them thinking they are "unique", unique environments, skills, enemies, plot, etc, and when they start repeating stuff it makes me really tired mentally. Take Devil May Cry, it's a "6 hours" game according to HLTB, just 22 or 23 stages, but they had like 4 bosses and they came again and again, 3 times each, so I grow tired, it's not a surprise or a shock but utter boredom.
Oh, and HLTB statistics, don't even get me started with them, statistics are so fucked up, since only hardcore people use it it says a game lasts 10 hours and completionist (I guess with a guide) takes 20 hours, but it takes me 20 just to finish the game. So I take completionist as my target time to finish the game. And others report the "in-game time clock". Sure, I finish the game in 5 hours and 45 minutes according to the in-game clock, but it doesn't account all the times I had to reset to load a file so in the end I spent 12 or so hours, over twice.
I try not to spoil myself looking at how many stages there are available, I like that being a surprise. However some games I felt they could have been better with less stages.