No idea tbh. Last time the wheel was up, I recharged a total of 100 spins and only got like four frags. This time, I've recharged a total of 20 spins so far and received 5 frags as of now. It's completely random and impossible to know how many times you need to spin or what even the general average is. I've never received a x5 frags reward though, only single frags.