I guess it depends on the type of pro-work, but in my experience I've found that if you follow a specific professional artist you can see their work grow and evolve. If we're talking comics, it's a bit more rare to get to track that down in the western sphere, with how little author-owned works there are
You see it in a lot of tv-shows too. The first season is generally a bit rougher and them trying to experiment with the format, with the 2nd or even the 3rd season where they settle in the style of voice of the show.
Oh I do not consider Trespasser my magnum opus at all haha. If anything it was the backlog story I had from a couple years before that I dug up again to rekindle my passion in a period of creative burn-out. I grew to care about it more and more over the course of making it.
It's also not the first thing I've worked on and I have experience in setting myself up a production pipe-line. Hell, I don't think I would have managed to make it as far as I have had I not. In fact, I actually treat each chapter as it's own thing too, each book starting its own cycle of production.
I wanna do shorter stories not because I grow tired of Trespasser or because I'm burned out by it, rather I'm more inspired than ever and want to do even more than I'm doing now haha. Hell, I could probably spend the next 50 years just making more Trespasser!
The problem I'm having is that I'm getting new ideas that are better served as their own unique world/story, instead of trying to cram them into this current existing thing.