My own experience is varied. I have compared a Super Kodiak that was unloaded everyday to one of the same poundage and year that had been strung for three years, there was some difference. I left a longbow built in the 70s strung for 3 months, it took a set that never quite came completely out. My daughter left her newer Hill Cheetah strung for several months, it took a very noticeable set, after two weeks it was back to normal. On the other side I left a Bear TD strung for a year and unstrung it lined up exactly to a new one, when the proud owner of the new bow asked if he could leave his strung.