I was thinking along the lines of someone like Annoura or some other Gray, who has been away serving as advisor to some ruler for ages, and who relies more on her negotiating and political skills than on the One Power on a daily basis, thus never really developing her strength fully.

Again, the reasoning feels a bit off, as over time you would surely rather want to reach your full strength than not.

But if it was a twist that gave RJ a kick, then I guess it is remotely plausible, kind of.