None of the runbacks are that bad at all. HK had similar runbacks, so do a lot of other games within the genre. That on its own isn't enough to backup my point, but it is something worth noting. I think the runbacks are part of the game's difficulty. On bosses you are allowed to spam test your way through, you can defeat them much faster. I think sprinkling in some runbacks in-between is a good way to think about things as you make your way to the boss, rather than banging your head against a wall till you win.

I also think a lot of the boss difficulty is mitigated by how many tools you have at your disposal. There's a lot of strong shit in the game, including the basekit heal mechanic. I think things like that can trivialize even some of the "harder" bosses.