I have been called for jury duty 5 times and actually served on juries 3 times. The first couple of times I got postponements but they seemed to stopped giving those, at least where I live.
My boss was late the first day of jury duty because of a flat tire (she lived 45 minutes away from the courthouse and there are no taxis on the long stretch between the two cities). The judge made her go into his chambers and then tore into her for her disrespect.
It all depends on the judge.