My Hercules has paid for itself over and over again. I do 15 minutes at a time and only use it on the edges after they have had at least 20 mins each of rolling. Even then it is light taps initially only. You only use the weight of the mallet head to knock for the first hour on the face and toe. You will crack the bat if you are not careful. Most factory made bats can be done in 3 -4 hours max. Decent bats like the forum sponsors and others sometimes need an hour or two max.