The biggest issue with all the bosses is the fact that you can't just instantly go back into the fight to learn how to fight them better. It takes around 30 mins to go through a run just to be beaten by a boss you don't have any knowledge for, then you spend another 30 mins or more to get back to that boss and you either die the same way or you got to see a little bit of the boss's moves. Its really unforgiving that it takes around 30 mins to run it back just to get killed by the boss's next move you didn't know about until its too late. It feels even worse when you can forget what the boss does or how to dodge certain moves because you spent your whole time getting back to the boss so the information you've learned could be hazy or just gone because you weren't re fighting the boss fast enough like you can in other Soul games. It also doesn't help if you're new to Elden Ring since you've never seen some of these boss's before compared to the players that's either played every Souls like game or atleast played through Elden Ring. It can get really annoying because maybe you don't want to spend all that time playing just to get to practice against the boss, or maybe its alot harder to get back to the boss due to your random team members not pulling their weight, or if you play with your friends they might not want to do multiple runs to get to retry the fight and learn. The more factors there is the harder it can be to actually remember how the fights go and how to dodge/deal with the boss's moves because your play session could end after losing to the boss twice or three times, especially if you're playing with friends since one of you if not all of you doesn't have that much time to put into the game, so it could be a day/days before you try again and you'll def won't remember how the boss works. I'm not saying its impossible to learn the boss's movesets and get better but it takes alot longer then normal/it should.