I don't really have that luxury.
It's awful to have a lot of half-finished things lying around. In their half-finished state they don't help anyone. But you can't swing to the other extreme and just work on one thing to the exclusion of everything else (at least, not usually). It's important to find balance. You need to do enough of the other stuff that things don't fall apart, while still making progress on your project.
So where's the balance?
- Set aside project time in large chunks - for me it's Mondays and Fridays.
- Meetings are meetings; don't bring project work (or any other work) into them. If everyone pays attention the meeting is actually likely to end faster. That means me, too.
- Set aside time for non-project work, and stick to it. For me this is Tuesdays between meetings and an hour or two most mornings.
What do you do to balance all your projects?