Quoted from Aurich:
Battlefields definitely don't all play the same. I forget what the 4th level requires in hits now, but I've beaten that. 75? Not sure I did that in one try, probably at least a couple.
So after reading this thread I decided to play for nothing but battlefield. I got up to level 5 or 6 I think--took 110 hits to finish. After that I think I discovered a game bug, because the dmd was saying I needed 188 hits to open the battlefield.
Decided to play the game out (I did accumulate like 5 extra balls in the process), ended up with a GC score around 2.5 billion! Was 2 shots from finishing final battle too--that would have been huge.