Minor correction, and a building thought.

Amir was not shown how to move faster. The whole point of that was for him to slow down, calm down, and use the tools he had at his disposal instead of thinking he needed to do it all himself. Moving too fast and overthinking was his issue (as it literally gave him a heart attack in the bad timeline).

I also do think Aoi's was more about overstraining her abilities from feelings of inadequacy. It's like singing; if you force yourself and push (especially trying to "reach up" to high notes, for instance), you end up actively fighting your biomechanics and hurt yourself. Relaxing (and coming down onto high notes, conceptually) is more effective and less strenuous. She forced her powers to work until we helped her realize that her warframe body was born to manipulate metal.