I would generally think that you would want tighten them during off season to get a little stronger and used to pulling the heavier weight. Than when season comes down you can back them down a turn or two again and have an easier pull when you have been sitting around a stand for 3 hours tightening up. Easy to pull a stiff bow when it is 70 degrees or more but when it is 7 degrees and you are cold and tired..Whole different story. A little offseason training on a slightly harder pull bow might do wonders for your strenght. I know it would help me a lot.