I think the most important thing is that the work stays varied enough to be interesting in the long term. If you aren't able to move to new projects you'll even

I think the most important thing is that the work stays varied enough to be interesting in the long term. If you aren't able to move to new projects you'll eventually get some combination of bored, restless, and burnt out. Then it might be time to reboot your career inside the company (if that's something they make easy to do) or you might find yourself ready to move on.