By that time it will probably only be enough for one level, I don't think that's worth it.
AND there are many instances in broken valley and such where you need to mind-read people at exactly the right time to get the benefit - you can't go back later.
I do use a variation on that trick myself:
I finish Maxos Temple, then if I'm close to another level, I go to Orobas Fjords until I level up, and then I go to the island and Mind-read it for another free level.