I am like Bernie, I don't move the hoop until I am ready to start quilting a new area. With poly batting it rarely leaves bumps or imprints and when it does they go away after a day or so. With cotton, because cotton "remembers" I have had hoop marks but they also went away after a while, just takes longer time. Once I was handquilting a cotton bat and I thought I had permanently dented the batting but it was completely nonexistant after washing. I wouldn't recommend leaving the hoop in for really long periods of times though (like more than a week in one spot).