When I came into feeders from package car (9 year wait) we drove 5 speed GMC's. The clutches were wet (full of ATF fluid). It gave you one more dipstick to check on your pretrip. We were instructed to double-clutch EVERY shift, or be disciplined. I did it for years. They did away with the wet clutches, but I still double clutched. On road Supervisor asked me why in the hell I did that? I was trained that way and never changed. Double clutched till my last day on the job.
I admire you if you could/can double-clutch all that time. I couldn't and wouldn't.
Came to UPS from driving OTHER trucks. Started out driving 5x3, then new 5x4, then 8-sp Allison with a 3-sp splitter (I know, I'd never seen or heard of one til then but got to love it later). Never did use clutch except when stopped, either reverse or forward.
Did the package car thing (not as long as some have), went to feeders, yes, with same setup--5-sp, wet clutch. Thot I was in heaven. Told to double-clutch. WHAT? OK, so did just to appease the instructor gods. Toughest task I've ever had to complete in years of tractor-trailer driving. On my own, DAMNED be the clutch!
When going thru a ride (at the time, they were supposed to ride with you every 3 months, right? Then got it knocked down to 1 a year if you were a good boy?), I, then, just flat out told em I wasn't going to. Too difficult and time consuming (for me). Most acquiesced and said if I snarked ANY gears, they'd write me up. Never did. They, on the other hand, when their turn...HOLY SNIKEY! Every gear was rounded off by the end of their shift. I told em I was gonna write em up. No humor.
Didn't do it for our 5-sps, 7-sps, 8-sps, 10-sps, sleeper-sps, or any other sps, we had.