I think there's a frustrating issue when it comes to manga vs western comics in terms of polish which is:
Most people in western countries have not read manga that is the equivalent of a cheap adaptation of Nancy Drew.
If you've ever spent time in Japan, and gone into the glorious treasure trove that is a local "Book Off" store, you'll know that actually there is loads of low-quality manga, absolute dross that's churned out as cheap commercial tie-ins or adaptations or just third-tier stories in less well known mags. The stuff we're getting in the West is usually such a narrow band of just like... the better stuff from the top magazines like Shounen Jump or Afternoon that's made by the top artists for a big audience who are core manga fans and care about quality. It's not indicative at all of the wider quality of manga produced in that country. Have you ever seen those manga that adapt a videogame and how kinda crappy they are.... Like, here's what the official manga looks like for Persona 5, a game with huge sales and a massive worldwide release:

This is.... roughly on-par art-wise with loads of mid-level sort of comics here on Tapas. It was probably made with the same kind of required turnover as a webcomic artist might need to work to. It's not bad, but this is the kind of level of work that it's reasonable to expect on that kind of budget. It's mediocre when you stare at it, like... the placement of the features on the faces is... well, it gets weirder the longer you look, but the thing is, I wouldn't be scrutinising this art like this if I was reading it, I'd be like "oh damn, what happens next! I love these characters! Yay, Persona comic!"
I've worked on that kind of Nancy Drew type commercial stuff (not Nancy Drew, but other similar IP). The deadlines are punishing and the pay is awful, even when a big publisher or IP is involved. There just isn't time to spend making it a beautiful Eisner-winning masterpiece, and most of the audience don't care because they're kids, fans who aren't usually comics readers and are more into the brand than you, the artist. To them, and the people who commission it, you're just a tool, and if you destroy yourself to make it look good while being within the deadline, they won't pat you on the back, they'll just keep hiring you and you'll run yourself into the ground for your pride, and it won't even get you anywhere, because the talent scouts at Marvel aren't looking at random licensed comics. You have to learn where to spend your effort and what's actually a reasonable amount of effort to put into a project or you'll burn out or destroy your eyes or your hands or your shoulders or your back...
So yeah, done is a hell of a lot better than perfect, and it's a lesson that if you don't learn it, you almost certainly won't make it as a pro. Comics are a storytelling medium, so if you sacrifice moving a compelling narrative along at a gripping pace, or getting the work to the client on time for making every page a perfect standalone artistic masterpiece, you'll shoot yourself in the foot either in terms of building a fandom or just making enough money to live, or you'll physically damage yourself.