I was only called in one day of my life so far, and what a day it was...
Jurors were supposedly freed after either one day of service (at about 3 pm) or after serving on one case (whether you were selected or not, no matter how long the case takes). The "worst case", of course, is to be selected for a multi-day trial. The best case... almost happened to me.
I was called in 30 minutes after I arrived. Me and about 30 others were rounded up and walked to the courtroom. I caught a brief look at the defendant, who had a deer-in-headlights look. The doors shut right in front of us before we could enter. We wait. 15 minutes later, we hear the defendant accepted a plea agreement. I was excited at the prospect of getting out at 9 am. We saw our one case, right? Right?
Wrong. Apparently they decided it only counts as a case if we walk into the courtroom (though their actual rules were silent on the subject). Fast-forward to 2:45 pm (yes, doing nothing for 6 hours in a room that didn't even have a TV), when the clerk tells us we're free to go at 3 pm if we're not called. One last batch is called at 2:55 pm. Yeah, I was in it.
A possible multi-day criminal case, "home invasion" involved (didn't they used to call that robbery and assault/battery?). I told them I couldn't completely stay neutral to the fact the defendant wouldn't testify (another pretty good way to get off, I guess). I got out around 8:45 pm. 13 1/4 hours of work for $15. As they say about the people who made it in: "What do you expect for $15 a day?"