I'm just a dad and former Little League coach, not a HS coach like Cabbage, so take my opinion with a large dose of salt. 8 of the most successful teams in MLB are playing right now. Why not watch those guys and see how many finish their swing with one hand on the bat? I'm thinking you'll see that the great majority finish with 2 hands on. Of those few that take the top hand off, I think you'll see that it stays on at least until they extend through the ball -- IOW keep the top hand on past the point where the end of the bat is facing the pitcher.