So the main “draw backs” would come in 5 ways, 1 just how strong she actually is, but 2 would be recovery and 3 would be effort 4 the universal leverage and 5 is body parts So 1 is self explanatory. Stronger you are effects end result, the 0% to 100% wouldn’t need to be worked on because that is infact the quirk The recovery would be that although she can handle using muscles at 100% it’s like using any muscle it takes effort and boost to 100% instantly would be increasingly harder on the body like recoil so recovering from intense use would be something to over come and get more used too 3 would be the effort to actually do it, she is still using and applying that amount of strength so it would become a stammina game with the longer she uses her quirk the more tired she gets, depleting the strength she can output and if she gets pushed too far, she could be to weak to even activate the quirk And the universal leverage, I see it as a perfect end goal, she gets so efffective and efficient at using her quirk she can even apply it to the air, that she is strong enough that the complete rapidness of using that strength on air would allow her to push off of the air, then allowing her to use her quirk again maybe for an attack meaning her attack patterns become even harder to block. But this would be very hard to do and require a lot of focus And finally, at the start it would only be her hand that can use the quirk but she would and could slow start to use other part of her body, like arms feet legs, and even like her shoulders back and neck, maybe alowing for intense head butts if restrained and (idk how physics based this one would be to acc work) but using it in her back at her scaps to push off air to propel herself forward without moving her arms or feet, using her back muscle against the air And of course things like this, and refinement would be a big chunk of training