It's not something I kept track of, but I can tell that after doing attempts for a while I could get out of the 1st hour of the run (so basically up to DOTK) most of the time, with just Razoff wrecking ball phase and Céloche still being issues at times.
Then in DOTK you had the Reflux fight, and the Lavicrafts fight with the really awkward camera that were always really though and definitely ended a bunch of runs. And whatever
this was.
Summit was mostly alright, snowballs, Lavicrafts and the room with the scaffolding at the end of Summit 2 cost a few runs but not the worst. I did lose runs to
something else than a hit there though.
HHQ1 room with the hanging boxes was hard with the hoodlums having the high ground and shooting at you from a bunch of different angles, and of course you had the Horrible Machine which could get really messy, especially when getting a lot of Hoodboomers. Both these parts were real run killers.
Questionable collisions also cost me one run in HHQ5.
Leptys 1 has to be the hardest level, the 4 Elite Hoodlums at the same time at the start, into 4 Hoodstormers at once and the 3 Hecklers simultaneously, add to this the nerves of late game, absolute hell. A good bunch of the already not so many runs that reach that point died here.
Leptys 2 was alright, you have really safe ways to do the Lavicrafts fight, the Hoodstormers fight at the top of the first room has quite awkward camera I know I've lost at least a run there.
Leptys 3 shooting section was really hard at first and but then RibShark told me to try to mash the shoot button instead of holding and it made the canon way easier to handle while still killing the enemies basically as fast, so it went from really hard to just hard (maybe I could've learn the enemies patterns to make that even easier but I never bothered). I actually lost a few runs to not being careful and
bonking a wall lol.
And final boss was not too bad, the few runs I lost there were just
very unfortunate.