@aja- God his lines are beautiful!!
I have always heard complaints from artist regarding time constraints. I know Bachalo and Mad used to really have trouble with getting issues out on time and from what I remember I think that is why they tried to go off on their own with Cliffhanger. Joe Mad, Humberto Ramos, Chris Bachalo and Joe Kelley all started Cliffhanger and their own books but to my personal dismay Mad got caught up in art for video games and released like maybe 6 of his comics and then the rest slowly followed suit. So I want to say the problem why we don't see a lot of great artist stick around is because of time constraints and not enough creative freedom is my guess. Though you do see Bachalo do every four issues of Uncanny then another artist takes over. That is too give him enough time to regroup and do the next four. I believe he used to do that on Gen X later into his run. I think his work has suffered in that he uses more simple quick lines then he used to.