In Philadelphia it's every year ... 1 day or 1 trial. Although, some people never ever get a summons. But if you're ever summoned, you can pretty much count on being summoned every year thereafter.
One of the first years, it was a trial that was going to last several weeks. I was excused when I explained I was the only developer and it would be a hardship for my company. A couple years later when we were asked if anyone had a hardship because this trial was going to last weeks, several of us asked to be excused because of work. This time, we were told work was not an acceptable reason to be excused. It was up to your employer to get a replacement or we'd just have to work evenings/weekends. Needless to say, I didn't appreciate that. Fortunately, I was not selected for the jury.
Last year, about an hour or so before we would be excused for the day, they needed a second panel because they hadn't filled the jury with the first panel of 60+ people. Of course, my name got called for the second panel. Turned out, it was a drug company that was being sued, and they expected the trial to last months. The drug company had a dozen or so lawyers, and by the end of the day, still had not filled the jury. So, we had to come back the next day while they continued jury selection.
I was finally excused late in the afternoon when they finally interviewed me. When I was asked if I could follow the judge's instructions, I said no. Should have seen the shock on their faces. Of course, they asked why not. I explained I can't always hear what people are saying, and if I couldn't hear what the judge said, I couldn't follow his instructions. I wasn't lying. Though it's not that I can't hear, I just can't separate what's being said from any background noise.
For the two days we sat in the courtroom, the guy next to me kept talking to me. But, I could only get scattered words here and there because of the conversations around me. Really not fun. Unlike most people my age, I can't blame it on rock concerts. In my case, it was numerous ear infections as a child and until I was in high school. After a serious infection in high school that I ignored for almost too long, I was finally tested for allergies. Turned out, I had mildew allergies.
During this entire process of waiting while people were interviewed, we sat on hard wooden benches. Of course, the chairs in the jury box were also hard wooden chairs! The more I looked at those chairs and the plush cushy chair the judge was sitting on, the more I got ... annoyed. How dare they expect us to sit on hard wooden chairs for hours and weeks. Bad enough the judge is making something like $163,897/year ... while the jurors get $9 a day. Oh yeah, along with a coupon for the local restaurants for like $1 off the cost of lunch. However, parking runs something like $22 a day.
I didn't mind jury duty when I lived in Oregon. I actually loved it. I was only summoned twice for Lane County jury duty from the time I turned 18 until I left Oregon at 40. In those days, Lane County jury duty was a week, and you weren't excused if you were on a trial that didn't last the entire week. But, seating was comfortable, both in the waiting area and in the jury box. Parking was covered by the county, and food was provided in the morning (fruit, donuts, muffins, etc.) Philadelphia had stopped doing that by the second year I was summoned, and all they had are vending machines.
I was actually rather shocked the first year I was called in Philadelphia. I was still registered to vote in Oregon, my car was registered in Oregon, and I still had an Oregon driver's license. Turns out, Philadelphia gets their list of names from everything.