Originally Posted by Geoff Archibald
Warm up sets I always lower but for max efforts I usually drop the last rep. If someone can convince me to lower the last rep then I will but I think that the risk of injury is greater and not worth the risk. I could be wrong and if anyone has a plausible argument that the risk of injury is small and that the benefit is large then I am willing to change my ways.
As noted above, dropped lifts get red lights in competition. Which means that technically you shouldn't actually count a max unless you lower the last rep.
But it's your back, so it's up to you to decide whether that benefit is worth the risk.
For training, as opposed to competition, one way to define a working max might be "heaviest weight I can lift *and* lower with good form." Depends on what you're trying to accomplish.