I think generally speaking, being prolific is rarely a bad thing- especially for personal growth/practicing skills. Doing a large quantity of relatively fast work is a great way to improve most any skill quickly (rather than spending tons of time agonizing over doing fewer "perfect" works).
That said, as others have already mentioned, I do think it's important to be wary of finishing what you've started even if you've got multiple things going on at once. I strongly believe that an author should feel comfortable dropping or sidelining projects as need be for their own well being (rather than forcing themselves to finish something just for the sake of it), buuut there is something to be said for building up trust in your readers with finished works (or conversely, breaking that trust if many stories are always popping up and none are getting finished )
It doesn't sound like an issue for you since you mention having completed works, which is great! But there is one creator from tapas that I always think about as my go-to example of "I don't follow their work anymore because they kept starting and dropping stories all the time". Their first work was really great and I was a big fan of it. After a few chapters they put it on hiatus for a while which was no big deal... until they started a new series a few months later. The first one never updated again. So I started following the new series but... it got a few updates in and then also went on hiatus, after which a 3rd story popped up. That 2nd one has never been updated again either, and now the 3rd work (which I didn't follow) is also on hiatus lol. I consequentially check in on their stuff from time to time but no longer feel like getting invested. It feels more likely than not that new stories won't make it far it before getting dropped at this point
My preference is to be prolific, but on one story at a time. I like to jot down ideas and thoughts for future story ideas for safe keeping, but rather than spending a bunch of time writing/drawing for a bunch of series at once, I instead take the "prolific = speed x quantity" approach and just do as much work as I can for a single project Not that that works for everyone, of course, but in that way I try to complete stories as fast as possible without dipping below a certain quality threshold, learn new lessons and techniques along the way, and launch into the next project even stronger!