walmart where I'm at is actually pretty good with tires and even oil changes. I stand out on the entryway and watch 'em. they talk more than work, but the work gets done, and they haven't made any rookie mistakes that I've seen.
I got 4 new tires for my van last week, had the blown tire in the back, with my torque wrench, I forgot to hide it.
so the guy got the tires on, and I watched him torque the lugnuts, the whole van was rollin' back & forth. then a 2nd guy got in and drove around the walmart building twice, came back in to the bay and torqued again. OK.. seemed impressive. I get the van and drive out to the parking lot, and proceed to loosen each lugnut and re-torque myself. one of the tire changers comes out to ask what was wrong, and I said, nothing, just making sure things are what I want them to be. so as he was explaining how he was trained, I found 3 lugnuts total that weren't as tight as the others. So I showed him and said it wasn't his fault, but his torque wrench is constantly set for 80+pounds and the tension is always "ON" and never relieved and with all the tires/rotations they do daily the torque wrench they use to me, and in my opinion is no longer accurate because of all the abuse. I told him his TW is as accurate as the $10 asian knockoffs sold at harbor freight!
They even used those torque bars that stop at a specified rating, but as they ran the nuts down with the wrench they were still pushing till the clicker clicked.