OK, first off, "Neat and workmanlike" doesn't mean what some think it does. You do NOT need to have your wires "all tidy" like in the proud photos on Reddit. That is NOT what "neat and workmanlike" means, that is a "stunt" which makes the panel un-maintainable. (the real motivation is, shiny copper scrap is $3/pound.) It becomes a morass of wire nuts when the person later decides to install a surge suppressor or generator interlock, forcing lots of stuff to move. You certainly should give every hot and neutral wire enough length to reach any breaker position in the panel, to facilitate GFCIs, future smart panel tech, and general moving things around for future needs. Routing to neatly organize that excess length isn't a problem.
So I think you are misunderstanding that requirement. Have a panel where all the wires go where they need to go, wire pairs or triplets are identified, conduit is properly fastened down, cables are managed appropriately per NEC for cooling, and all unused knockouts and twist-outs have covers on them. Stab limits are respected.
Oh, and one extra-workmanlike feature is to use an actual wire for the neutral-ground bond, placed so it's easy to put a clamp ammeter on it. This can be a useful diagnostic aid.
What is Plug-On Neutral?
"Plug-on" is the term-of-art that describes how your breaker clips onto the bus stab. (the alternative being "bolt-on" such as Pushmatic or BAB).
If you've installed enough GFCI breakers, you have attached many white pigtail wires from the GFCI breaker to the neutral bar. Plug-on-Neutral is very simply a way to get rid of that GFCI pigtail. It's a time-saver for builders, worthless to DIYers.
Separating ground and neutral
Neutral is not ground. Exactly one neutral-ground equipotential bond must exist in one place - the first disconnect past the meter*.
Now, if that one place happens to be a classic "main panel" with main breaker and other breakers, since they're bonded here anyway Code grants an exception where here only, ground may be a guest on the neutral bar. If you're not in that panel, you must have a separate neutral and ground bar, and that's that. But even so, neutral and ground must go to separate lugs, as pairing a neutral+ground on the same lug is not acceptable.
Our Be Nice Policy prevents me from expressing my opinion to any depth regarding the drawing you posted... so I am limited to calling it "erroneous". Whether it would immediately trip or "Work, and then kill you"... I don't see any value in analyzing since it is simply........ erroneous. :)
Generally, ANYTHING that involves combining neutral and ground is going to be the Watergate (Oceangate?) of wiring design. It has been a dumpster fire every time it's been tried - from 3-wire feeders on subpanels, to groundless dryer and range connections banned in 1996 that still kill several children a year, to Britain's TN-C-S service wiring that makes EV charging insanely complicated there.
Like I always say, if you combine neutral and ground, it's not ground anymore. It's neutral and you don't have a ground now :)
It sounds like you are fairly new to electrical. I promise all this will make more sense as you level up :)
* Excluding disconnects labeled "Not a service disconnect" - that's a neat trick that can save you retrofitting a ground wire.