I work alone and it takes me far longer than it really should! But it's early days for me and I'm still learning.
So far I've found I work better one page at a time, rather than doing each step on multiple pages together. I'm not sure why that is although when I can see the panels getting towards completion it feels much more like I'm making progress, so maybe I just want to get to that point more frequently.
Anyway, it takes me between 10 and 20 hours to do a basic 6 panel page, although there are a lot of stops and starts in that time so I'm not sure how quickly I could do it if I could sit down and do it one go