How does auto shift work in a rig

I've driven both an old, Autoshift Volvo when I was briefly at Andrus out of St George. And also a newer, Ultrashift Volvo during my last year at Ruan. I don't know if it was just the age of the truck, but that clutch+autoshift was a pain at hairpin backing.
Forward and reverse several times, then the thing didn't properly go into gear unless you disconnected the battery and reset everything. That was back in Jan 2012 and the tractor was a 2000 model with more than it's fair share of miles.
The Ultrashift Volvo was a 2015 and even with hauling sloshy, milk tankers, that thing performed surprisingly well compared to that ancient brick I briefly drove. Only thing that I didn't like was that if you got stuck in the mud after a horrendous rain storm, you'd need a tow out.