If I get stuck in a longer queue, I spend it drawing... or trying to.

I'm a bit slow to start sometimes, so I can easily waste a solid hour and a half just staring at a blank canvas for lack of ideas/epiphany about the ideal execution for a particular piece. Since I've kind of forgotten how to just doodle, every single thing I draw is a fully shaded affair, so, between mapping out a piece, doing the lineart, and coloring it, it'll take me far longer than any queue I've experienced thus far.

If it's not that, I just chat with my FC, vacuum my house, brush the cat, etc.