I pull 35 foot of 5th wheel from Kansas to Travis AFB, Ca. I just put it in automatic and forget it. Do use the T/H going down grades but that's it. To lazy I guess. I did try the M mode once, but wasn't sure what it did for me. T/H is great for coming down Tehachapi though. Great tow truck.

 

Everybody does what works for them. I tend to only use T/H when coming to a stop or descending a hill. I have found the higher rpm shifts to be unnecessary and consequently hurt fuel economy. On the highway there is absolutely no benefit to using T/H.

The transmission seems to work fine either way and even works well in manual mode if you are so inclined.