I used to go for 5 or so days (never had an oozy infection but did have red bumps) but eventually realized that insulin absorption tapered off after third day or so. I didn’t believe it until I started charting blood sugars and saw that after the 3rd day, I tended to run higher overall.
And Suzanne is right about the need to rotate! I relied too much on the area below my bellybutton, which didn’t hurt. It didn’t hurt because it was waaayy overused! So I’ve branched out, up higher on my abdomen and further out to the sides, to ensure more real estate.
One thing you can do to force yourself to change sets is to put less insulin in your cartridge so there’s just a little more than you need for 3 days. Yes, you’ll go through more cartridges and sets or pods, but better rotation and avoiding scar tissue means more years of successful pumping.
I also write the day the set is due for a change on the set with a permanent marker. When I take a shower and see “Tues.” on my set, it’s easier to remember to change it. I told my pump manufacturer they should create an alarm that can be set for every third day, but so far they haven’t made that improvement!