Are there many cases where mole removal lasers cannot remove all of them at once?

I thought mole removal laser treatment would be a one-time thing, but
I heard that sometimes it is done in multiple sessions.

I heard that if a mole isn't a big one like a wart but its depth differs from what you see with the naked eye, it needs to be removed multiple times.

I'm not sure how many times that means... Are there some kids who just never drop out?