Power, if you are cleaning your rifle between sessions the result of a high POI can be the effects of oils or cleaners still in the bore. I make sure to run a patch soaked with rubbing alcohol after I have cleaned and a few dry patches behind, this ensures i have removed all cleaning or oil based soultions. In turn it results in no shift of POI through a clean barrel. You can try shooting a group of 3 or 5 leaving it until later or the next day(don' t clean) and see what happens then. I think it is imperative to ensure a cold barrel shoots on the money as this is mimics our hunting situations best. While follow up shots can and do happen, often your highest % shot is the first! Otherwise why spend all the time on the range preparing for that perfect shot, only to need/bank on the second, third or fourth rushed shot to connect.