User blog comment:Zathronas/Analysis by an author: Volume 2 episode 11: No brakes/@comment-3146930-20141024021616/@comment-10380701-20141024035455

I don't get what you guys are arguing about.

Getting hit builds up her semblance, which gives her some energy on reserve.

This allows her to punch harder, but each stronger punch eats up a reserve, just like how in Street Fighter, an EX Shoryuken takes up a portion of the super meter and how a Shinkuu Hadouken consumes the entire bar.

Once she uses it up though, it's gone. Rationing that energy is important.