Health bloat on enemies is a very precarious thing to balance, but in my opinion only a real problem if the actual execution of fighting the enemy itself is dead boring. If you can already perfectly no-damage a boss 99% of the time, then said boss having tons of health merely drags out things. But if you don't have the boss down to a T, the large amount of health is there moreso to force you to get to grips with the boss itself. On a theoretical easier difficulty you could barrel through a boss by sheer luck more than anything as you can kill it before it throws out its most dangerous attacks at random or before it can sap all your health and estus flasks.
When the boss has enough health to not be killed in ten seconds, he'll inevitably cycle through all his attacks which you'll inevitably have to learn to not get hit by them. It's what made the Nelo Angelo 3 fight in DMC1 on DMD really work as your double healthbar could be deleted in three-four swings and his took forever to get down. You should know his patterns by now, but it takes some skill to be able to execute the necessary strategies to deal with said attacks consistently rather than beat them by lucking out once or twice. Sekiro relies a lot on tight reaction parries, so I don't think this is too much of an issue. I only found it a problem during some mini-boss fights which barely give you an opportunity to damage their vit but have ridiculous posture regen/maximum posture anyways, like the Snake Eyes with Bell Demon on.
In Sekiro a lot of the bosses' final phases tend to be easier then the ones before, because the bosses start opening themselves up a lot more. Genichiro and Isshin will start spamming lightning which you can easily reverse for free damage and a stun, Headless Ape has more predictable swings and an overly telegraphed overhead swing which when deflected staggers him for free damage (while also being susceptible to the spear trick), and Owl starts doing that smokescreen stomp which is easily punishable.
For the Ashina Bros. fight you can delete Genichiro in half a minute if you know what you're doing and Isshin's first phase in around the same amount of time if you never stop letting up, it's only the second phase that's really tricky (while the third is about the same but gives you free lightning, see embed). I think in Sekiro's case you're given enough avenue to power through bosses if you know what you are doing (except for arguably Demon of Hatred). It's not unreasonable for the final boss in a game to have more HP than is the norm.
When the boss has enough health to not be killed in ten seconds, he'll inevitably cycle through all his attacks which you'll inevitably have to learn to not get hit by them. It's what made the Nelo Angelo 3 fight in DMC1 on DMD really work as your double healthbar could be deleted in three-four swings and his took forever to get down. You should know his patterns by now, but it takes some skill to be able to execute the necessary strategies to deal with said attacks consistently rather than beat them by lucking out once or twice. Sekiro relies a lot on tight reaction parries, so I don't think this is too much of an issue. I only found it a problem during some mini-boss fights which barely give you an opportunity to damage their vit but have ridiculous posture regen/maximum posture anyways, like the Snake Eyes with Bell Demon on.
In Sekiro a lot of the bosses' final phases tend to be easier then the ones before, because the bosses start opening themselves up a lot more. Genichiro and Isshin will start spamming lightning which you can easily reverse for free damage and a stun, Headless Ape has more predictable swings and an overly telegraphed overhead swing which when deflected staggers him for free damage (while also being susceptible to the spear trick), and Owl starts doing that smokescreen stomp which is easily punishable.
For the Ashina Bros. fight you can delete Genichiro in half a minute if you know what you're doing and Isshin's first phase in around the same amount of time if you never stop letting up, it's only the second phase that's really tricky (while the third is about the same but gives you free lightning, see embed). I think in Sekiro's case you're given enough avenue to power through bosses if you know what you are doing (except for arguably Demon of Hatred). It's not unreasonable for the final boss in a game to have more HP than is the norm.
