What the OP was referencing is skip shifting. You can run up through the gears empty much quicker than loaded. When loaded your target is 300 rpm. When empty, you rip through 300 too quickly, so you start off in 3rd, jump to 5th at 600, hit the split and continue through the high range. Procedure would be the same in 13, 15 or 18 speed. 13 is a variation on 9, 15 is a 10 with super low, and 18 is a 13 that lets you split the low range box of the trans. As for synchro trans, if you mesh the gears right, it doesn't hurt it. The problem is, in light duty vehicles, the trans is a lot tighter and the gas engine slows down a lot faster than the diesel in a heavy truck (less rotating mass and the throttle butterfly) so you have to be perfect and quick on the shift. The heavy transmission gears have less preload and the engine responds slower so you have more time. I hate the autos in even the medium duty trucks. We have a new chip box with some weird kind of pushbutton auto similar to EF auto shift. It sucks. I'd much rather have to row the gears. I don't like the IH super 6 or the spicer 6. The 7 isn't bad, but at that point, why not a 9 or 10? You know what the Operators say? Trucking only takes a 9th grade education. (Not to start any crap with the professional drivers, I've done it, it's hard, my hat's off to you, and I can't take it).