What kind of failure are you experiencing? We usually swap between our sons right and left thigh - top and side, cannula up and cannula down…we have 8 spots total and one spot (top up for instance) doesn’t see action for 18 days after we remove from that spot so that we keep his skin fresh and avoid occlusion, site irritation, and allow for healing of hole made from current POD.
Back in 2018 I did post about a bunch of POD failures all at once from the same box, but I don’t believe I’ve had issues with back to back boxes causing errors. My son has been using PODs since 2016 or so and we very rarely have errors.