I change bags with an urostomy every Sunday, so I get 7 days. After the bladder removal surgery (due to GYN cancer) I was told to change it every 3 to 4 days, the management of it became overwhelming. Once a week is not overwhelming. I never thought of going past 7 days, concerned about UTIs due to bacteria in the bag. Like you, I am meticulous about the skin cleaning and use the ring and the skin prep wipes. Interesting that you get 9 days with the urostomy, wow!