Im usually excused after waiting a half an hour.
The last time I had to sit in on a jury pool I was called to be on a jury for a mass murder trial.
I sat there two days while the lawyers excused one juror after another.
It got down to where the lawyers only had one more juror they could excuse, then the jury and alternates were set, and (luckily!) I was the last person excused.
I actually would have been excited to be on that jury, except the trial lasted 5 months!
Whew!