Installing one without tearing it
Housekeeping damage is the usual reason an encasement gets replaced early, and nearly all of it happens in the first two minutes.
Lay the encasement flat and unzip it fully before you lift the mattress. Slide it over one end, then walk it down the mattress rather than dragging, which is what splits a seam. Seat all four corners before you close anything. Zip to the very end of the track, fold the BugStop® flap over the slider, and press it down. That flap is what seals the last inch, and it is the step people skip.
Then leave it on. An encasement is a barrier only while it is closed, so it stays through turnovers and goes through the laundry rather than coming off.