Is that really how it is though? I have seen a lot of webtoons with random schedule, frequent hiatus, and incredibly long breaks between seasons. Unlike Japanese publication that have very strict schedule, webtoon always feels a lot more lax when it comes to scheduling.
Webtoon = Digitalized, contract based and season planned. Breaks are expected.
Manga = Print, fixed publishing schedule slot, break = risk sales = career threatening.
Long breaks in webtoons doesn't risk the platforms performance entirely but can be risky to artist as contract doesn't always guarantee income during break, so some will try to push through. It's the same with manga but a little less brutal.
+Contract differ to each webtoons. Some are stricter, some are looser. So yes, beside personal reasons, contract matters in webtoon publishing.
And a webtoon can always switch their artist team, so some can afford to be picked up even after being put into very long breaks. I don't think that practice is common in mangas.
This case is only if the writer and artist are different tho.
I understand that there is contract involved, but I always get the impression that the creators have free reign to how long of a break they can get. Maybe there is limitation like it has to be within a year, but I have seen them talking in their creator notes about estimating their break time and not being particularly sure when exactly they will return. On top of this, the length of each webtoon is never the same. It seems to be entirely at the creators discretion. They can make it as long or as short as they want to. In other words, their work schedule seems to be very flexible.
As for Nerd Project, I feel this isn't the case where the author is forced to end the series earlier because of the contract, but more so because the author may feel their body is reaching their limit, and the uncertainty of whether they could continue even with extended break make them choose to end it earlier. At the very least, I get that impression. I could be dead wrong.
Same answer, can differ to each webtoon, some are strict, some are loose. Webtoon industry in general is more lenient than Manga industry. But brutal anyway.
I'm also not entirely sure what the actual reason is, but i think people should also take into account that it's an actual job, not a hobby they can leisurely drop and pick up. And once a creative burns out, it's almost impossible to recover So it's a bit frustrating to see people "I'd rather they take a break" because it really isn't that simple sometimes :')
To the people pushing the "artist should've taken a break instead of rushing". Besides health issues and other stuff that might've effected the ending. Comics like this under companies have no such thing as "slowly at their own pace" because there's a contract behind it. If the artist was independent, it might have been possible. This is honestly the best case scenario instead of getting canceled entirely.