I work on Errant solo. It was something I really wanted to do after having spent years working as an illustrator and games artist where I pretty much had to spend all my time working on things for other people where my input was always limited to "just draw/paint the thing they asked for" and then I never had ownership of what I created. I'd become increasingly aware over time that while I'd never thought of myself as "a Writer", by my thirties I was consistently a more qualified and experienced writer than the majority of people I was working for who gave themselves that title.
My personal creed is "if you want a job done properly, do it yourself, and if you don't know how to do it yourself, go crack open a book and learn it". If I ever took on other people on a comic, it would either be people to do time-consuming but comparatively low-skill work like flatting, or I'd look for somebody who can definitely do the job better than I could alone, either because they're just more skilled through being focused on that exact skill rather than being a generalist like me and to a degree where there's no way I could reasonably just learn to do it in a sensible timeframe, or because they're more suited to the style or tone.
Every person you add to a project increases the chance that the project will fall apart partway through, especially if the pay isn't good and reliable enough that being invested in the project and prioritising it is important (ie. it's paying your rent). More people to have fallouts over creative differences or personality clash, more people who want to have creative control of the project and get frustrated if it's your "baby" and you want complete creative control, more people to get caught up in life events... it's just a big risk, so I'd only add people if I had reason to be very confident they were sticking around and if adding a person would definitely raise the quality and/or output speed, OR if the collaborative component was important. I'd never add somebody to say... draw the backgrounds because it's not as fun as drawing the people. I'm not going to risk a project falling to pieces by relying on somebody else to get the backgrounds in on time every week for a weak reason like "drawing backgrounds is hard and takes time to learn". I'd rather just suck it up, learn to draw them and get my comic done.
