None of the mechanics I know use anything but a floor jack to change a tire. They use a "real" commercial quality floor jack, and most of the younger guys put the tire on with their legs under the car so they can raise the wheel up with their knees. Nobody really goes under a car without a jack stand, but I've never seen any of them bother just to change a tire.
Dunno, We got fired if we did that. Of course, real mechanics don't use floor jacks. They use air/hydraulic jacks that have a lock. You gun it up, and then set the lock. Safe even in an earthquake, unless you are at the epicenter...
Guys raising one wheel are not mechanics anyway. They are tire guys or helpers.
The illegals that work the cheap tire shops in my town take serious chances every time. They raise the car with a cheap jack, don't bother with stands, shake the cars, climb under them, etc.
However...
Most of them have a goal of being injured on the job.
The way workman's comp is structured here in the Golden State, it's an Illegals way of getting free training, lots of cash and legal status. Go to the workman’s comp retraining centers in your town. Play a game. Try to find the Anglo. Lots of luck.
I don't put anything under a car not on jack stands because when I was 20 I yanked a falling car off a buddy. Saved his ****, but to this day I get twinges in my back.
How much is 1 minute worth to you?