Power feeding is forcing your snake to eat more. So we all know that's not right. Over feeding is feeding too much and/or too often. I don't think you really can over feed a BP. I have never ever heard of a "fat" BP. They are probably the most self regulating species of snake. Unlike a boa, when they don't want no more they won't take no more. Due to what we know about their digestion, even if you are feeding an adult BP mice because they are anal about it, it would be better to feed them all at once than to spread out over a week.
That said....
A lot of people will say "7 days" but I know from my years on these forums and elsewhere that that is a PC term. I know plenty that feed breeding females every 5 days or do a 3/4 schedule like Sunday/Thursday or feeding something larger than normal every 7. And I have never seen any report of a bad outcome from that.