Genichiro Ashina fight from Sekiro took me 3 days of multiple 15-20 mins sessions.

With each attempt you learn the attack patterns and tells of which move-set boss will use.

Its immensely satisfying to slowly learn and see yourself improve.

When I eventually beat the boss I felt like a badass.

But most importantly its memorable experience, something that is hard to create.

From Soft can created hard but fair experience, and that's what makes the unique blend of emotions while you slowly master the game/boss.