Do One-For-All users have different training experiences?


While training his successor, All Might is often surprised by Midoriya's
abilities (or lack thereof) to control One-for-All. He notes things like, "I
guess you can only use 5% of this power right now".  
  
Were All Might and previous users just more adept in adapting to this Quirk?




Yes, the other successors for One-For-All were handpicked by the previous
users among the fittest to use the quirk. Gran Torino mentions that even
though Toshinori/All-Might was born quirkless, he possessed great resilience
and endurance to maintain One-For-All power.

Midoryia had no previous training nor did he have a good constitution or
muscle strength to keep up with One-For-All's great stress upon the body. That
is why All-Might has often had those remarks about him.




Yes, the other successors for One-For-All were handpicked by the previous
users among the fittest to use the quirk. Gran Torino mentions that even
though Toshinori/All-Might was born quirkless, he possessed great resilience
and endurance to maintain One-For-All power.

Midoryia had no previous training nor did he have a good constitution or
muscle strength to keep up with One-For-All's great stress upon the body. That
is why All-Might has often had those remarks about him.

