Powerfeeding is offering a lot of food at once or feeding too often, all to make the snake big, fast. Yes, this type of thing CAN harm the snake. They will eat as much as they can hold since they never know where the next meal is coming from. You could feed several prey items once a month, but this is still harmful since the food could rot in the stomach before it ever gets digested. Feeding every 3 days means the snake never gets the chance to rest after moslty digesting its meal. Digestion for a snake takes many days and it requires a LOT of energy.
If you haven't done so already, please read
this caresheet
