Who is downvoting OP?

He's right, you don't have to hit everything to the beat. You get bonus damage if you do otherwise it's automatically synced to the beat regardless of when you put in the input.

There are some dodge/insta-kill segments that are literally like a Pa Rapa rhythm section but I believe there are things in the accessibility section to give you a bigger window and only do one button if you can't hold a beat.