I'd assume because some dudes have healed wounds at kinda suspect rates. Like Jotaro being skewered through the leg (Enya), but he's fine at least within a week or two the next time we see his leg, zero wounds.
Or getting stabbed through the shoulder (Strength), and is fine days later. But not all users show this, so idk if you'd say it's a stand user thing opposed to a that character in particular thing.
Josuke also is a bit suspect, he can't heal himself so all his wounds healed normally, and usually days apart at most as all of Part 4 takes place over 2 months.
A lot of characters have an excuse due to healers, but some dont, Part 3 notably, I'd say Joseph was healing them off screen but he explicitly says at one point he hasn't used Hamon in quite awhile so Hamon healing some wounds wasn't actually happening off screen.
I'd say maybe Araki just forgot, but he DID keep Pol's tongue wound for a few chapters (when he got stabbed in the tongue by Justice, he has a bandaid on it in the following few chapters) and well Araki has shown scar tissue and the like to indicate past wounds or extensive wounding over a length of time so eh. I wouldn't say it's a universal thing though, given characters like Abdul and Kak needed quite a bit of rest and medical attention opposed to a mad lad like Jotaro who just, doesn't give a **** about if he should or shouldn't have wounds.
Wouldn't be combat applicable or anything but, a few dudes do heal faster than what's realistically possible so I mean
Size manip would work for any stands that manifest in such a way, (SHA does that too in Part 8, shrinks down to enter a blood vessel to blow up a clot) so it's actually a thing still, just never ******* used because I guess (It only ever being used to invade bodies in hyper specific circumstances is probably why, with the latter being what is effectively a doctor). Wouldn't work for formless or bound Stands but Stands comprised of like, Stand energy could, if they knew they could at least. And while noncanon, Star Platinum and Kak do it in Genesis of the Universe against Absalom.
Not all Stands have flight, many do but that's more for the types like Star Platinum or Chariot, who can just fly around in their effective range, but something like a bound Stand, stands without form, and more like The Fool, FF, Strength, Devil, Oasis, etc can't fly.
In most cases, instead of saying "all", I'd switch it out for "most" or "often", because there isn't a single rule that actually applies to all Stands, every single one has been broken at least once.
Also, probably need to tweak a bit of the wording, so it doesn't count as plagiarism.
