You really want to avoid scar tissue by changing every 3 days and rotating sites. I have a spot on my stomach that I cannot use for an infusion set because I did my shots there for 10 years or more. I don’t have any dents there but it is a useless spot for infusion sets now which is frustrating. I have a friend who pumps who uses the same areas over and over and leaves his sets in for 5 to 6 days at a time. Now he has 4 areas that are super infected and his BGs are all over the place because of the infections. He has to go see the doc for antibiotics now. It’s not worth the risk. You can always salvage that left over insulin and use it again if you want or just don’t fill your reservoir all the way up when you change sets. Let me know if you want tips for salvaging the left over insulin, I have it down to a science 
