i have 4 and been claving mine everytime for over a yr as well. i only do one 4-10 hr session per day. I don't think bagging is really that adequate when you take the carts in and out. i use true tube grip covers and wipe down the grip with germicidale wipes. then sonic for only about 2 minutes to avoid losing the anodizing and then they get rinsed, bagged and claved. I'm wondering what the deal is going to be with the new Cheyenne Pen machine.