[slowmover]

See the 2011 discussion: What is Engine Load Percentage (Ultragauge Question).

My long winded bit above is more icing than cake. Trying for context. Throttle is always going to be moved or dropped, long periods of no throttle in anticipation of downshifting, etc. How to be smooth in transitory states, I should have stated, is the meat on the bone. Not exceeding 80% of maximum means a limit on throttle movement to change from one state to another.

Driver has to be well out ahead of the truck (as pilots say of aircraft). Throttle changes may no hurt as much as with a gasser, but extended periods aren't warranted either. I'd rather drop gears, and then transition back up.

In a loaded pickup towing a fair sized trailer, this may mean slowing more than one expects. To drop a gear. And then another.

The rule for hill climbing is to drop low enough in gearing to be able to accelerate up the grade. That's usually the gear with which to descend.

Alternately, in accelerating onto a highway I don't wind the truck out till Fourth. Redline in Fourth and Direct really works. Makes up for being slow in lower gears as one can now maintain boost between gears. (Assumes a busy highway). Don't slide into Overdrive too soon. And get out of it (towing; heavy) early. Thus the bit about long periods of waiting. Feels long. (That how to shift business). With "80%" as an upper Engine Load limit, tailor other matters to suit.

Experiment.

I've run the big truck 6000-miles now. Learned to control that fluid slosh. What cruise control speed is best based on usual parameters. Same geographical region and temps. Overall average is from 5.8 to 6.5. Or, 12%. (That would have you to near 14-mpg).

"Feel" is crucial. Big picture versus details of gauge readings.