You either invest on the front end through testing or the back end through repairs. Either way, you pay.
IMHO, Cheaper to burn-in and test up front … having your customers do It for you is expensive unless you don’t plan on doing repairs or keeping customers. And there are other benefits ….
Back when I was designing hardware sometimes the part tolerances were too tight (read that as too expensive) to get every unit built to meet spec. By opening up the tolerances, it was well worth letting some percentage to fall out (in testing) to be reworked. The rework was cheap for the few units which fell out for this reason. The testing was being done anyway.
