Hi David, I'm relatively new to insight pump June 16. I was advised I need to change my cannula every 2-3 days and my tubing every time I change the cartridge. My cartridge usually lasts 4-5 days so I do a cartridge, tubing and cannula change on those days. It works for me as then I am not changing cannulas in between.
It's never set in stone and you will find out what works for you. This is my experience and I haven't had any problems with cartridges, tubing or sites but I know people are given varying advice from their Diabetes teams.
Hope it helps