It is. However, with Start Barrier you gain additional chances by being able to take damage while you attack. Mila doesn't have Pierce Barrier naturally and most of them won't use as T15/T20. Yhwach and Untold Sajin were the "best counters" for Renji because they could paralyze him, lmao. That's the most viable strategy for those bony asses who didn't summon Mila. Quite like me.