You ever switch from a flat to a step deck and you'll have rookie marks until you learn to remind yourself that they are loaded completely different.
Trust me I found out!
I get a different trailer every time I pull out of the yard. (I know, I'm just a lowly company driver.)
A 48' or 53' flat, sometimes spread, some adjustable, some fixed, sometimes sliding tandems, sometimes fixed, and a couple that are stretch setups (very heavy). A 48' or 53' step, sometimes spread, some adjustable, some fixed. A 48' or 53' Quick Draw (Y'all back East call 'em Conestogas), some step, some flat, sometimes spread, some adjustable, some fixed, sometimes sliding tandems, sometimes fixed. A 48' double drop. A 48' double drop extendable. A 48' or 53' curtainside, some step, some flat, some spread, some tandem, some adjustable, some fixed.
And they even have a couple dry boxes (I know, I know!) because the largest account they have has the occasional odd load that absolutely must be moved in a box, and they don't want to broker it out. Makes for a nice change of pace.
Some of the older trailers are all steel, some are combos. Most of the newer trailers they are buying are all aluminum.
Having such diversity of equipment makes it a real challenge sometimes. And if a driver is new to flatbed work, they won't be a r00kie for long. You learn quick or go back to boxes.