It actually is spammable, or at least to way more of a degree than you might think (I'm assuming you're thinking of MIH Arc where Jotaro had to wait a few moments between stops, normally the gaps between aren't as long).
The inability to spam stems from a stamina issue, most notably post-coma because well, he literally died, was frozen, got revived, and became comatose for 4 months where his body and spirit atrophied away to a large degree (That sustainability drop in that arc from an A to an E exists for good reason, bro got nerfed hard).
We actually removed that weakness about 2 years ago, it's only a weakness in Part 6.
Because if this is the case, Star platinum would be thousands of time faster that every opponent in this matches, which itself makes the matches a massive stomp
According to speed rules, apparently, weapons, items, attacks and so on that have a different speed value get lowered by the same
relative amount as the main fighter, so yes, Plat does get equalized but he still holds that same relative difference to Jotaro as he usually does.
It is important to note though that Star Platinum can only move
within 2 meters of Jotaro.
Its highly limited range offsets its tremendous speed as an actual canonical trade-off (Power-types have short-range explicitly due to having high stats).
Characters that Jotaro faces don't have to worry about getting blitzed unless they get within 2m of him, but at that point, the fact they probably can't see, sense, or harm the invisible ghost man is likely far more problematic than the fact they're likely getting punched a bunch. But for future reference keep that in mind, the threat of getting blitzed by a Stand is only an issue if you enter its AOE, and some Stands actually get slower the further they move away from the user too, all important caveats you can use in the future.
https://cdn.**********.com/attachments/1070940734380847195/1070942655921524798/Untitled32_20221214214612.png
Of course, the first one is super unfair and the second one Jotaro gets stat checked regardless so uh, yeah.