Is it bad to skip gears while loaded (13 speed)

Yes that is the majority of truck drivers

 

Its easier to wreck a 13 by using the splitter than by avoiding it. Especially on old 13s.

 

Ah you met him

 

Doesn’t anyone have anything to say on the part about the hidden 4th high gear the op mentioned?

 

My best guess is the splitter lock out was worn or someone attempted to remove it.

 

Think'in same. The driver that told him that..I wouldn't hire him ( if I was hiring) to drive my wheelbarro.

 

There is a “hidden” gear on the high side in low gear hole. You go into it when you hi range outa 4th instead of going into 1st hole as your first normal highside shift. They say its a big no no. I know guys that use it during turns because its a tad slower than 5 th. It is basically like being in 4th but being in the high box already.
Easier to use with these old style 3 position knobs like mine.