Well, one might wonder what the point of upping the level cap is if there isn't any content for capped players. We also have the XP speed up option if the game starts to feel too grindy. But I can dig the argument about being roughly appropriate for all stars, which is around level 50. So I'll try it in that range and see how many HP makes sense. The fact that we have a few endless modes will hopefully be a good offering for high level players to try to optimize.
Regarding time wasting, I don't see the super sheep as a time waste, unless I suppose you keep failing at it, which would suck a bit. It doesn't take 30 minutes, at least on 4x (which you should be able to mostly do). I haven't timed it precisely, perhaps I should. Either way, I see it, along with Endless 2, as somewhat cathartic. It lets you stop worrying about health and protection and various paths and instead just deal out crazy amounts of damage. I'm sure not everyone agrees, but that was the goal of the level (along with providing a silly super boss).