Currently working with a couple different publishers. It all varies from publisher to publisher. Some are very hands on in the editing process and some just let you go do what you’re gonna do.
For a graphic novel you’ll have a turn in date that you can negotiate. Everything is negotiable. Contracts are literally made to go back and forth until everyone is comfortable with the terms (and that goes for things like deadlines, advances, media rights, etc).
As far as “are they strict with schedule?” Well, yeah I mean you should try to meet the deadline. The stakes are high and if you’re working with a publisher they’ve probably paid you an advance and if you can’t deliver you basically owe them all that money back. And advances can go into six figures. You don’t wanna owe someone that much money. Its not uncommon for books to be a little late but you don’t wanna have a reputation for being unreliable.
As for quality, well, you’re not gonna get in the door if they don’t like your work. Most people on the publisher’s end aren’t artists so you’re likely not gonna get a ton of notes like “this perspective is off” but this also probably varies from publisher to publisher. But generally if you’re getting published you’re probably presumed to have a reasonable level of polish and professionalism in your work. A publisher isn’t there to teach you how to draw or how to write. You need to come in with those skills as a professional.
I like working with publishers because the money tends to be better, I can make my own schedule and work in bursts and take breaks when I need to, industry people pay more attention (specifically comic and animation industry people), and the reliance on social media pretty much goes away if you’ve got enough success with publishing.
I don’t think its someone people should just try to jump into. If you’ve never finished a 160 page graphic novel you’re probably not ready to start pitching. A lot of the bigger publishers don’t even take unsolicited pitches or un-agented creators.
The most important stuff I think is:
Know when you’re actually ready, submit everywhere (even if you think your work isn’t a good fit), look into getting agented, and read/understand/negotiate your contracts.