It's difficult, but what they do for grand jury is that unlike a regular jury, it has set days in the week that it operates. For us it was Wed and Thursdays. Also since we worked for the state attorney basically we had lot of protection from losing our jobs since you can't be fired or such because of jury duty. One jury member for example was getting harassed for missing so many days but the State attorney as well as a judge set the employer straight on the matter.
We were paid $15 a day, nothing more, though we got free parking at the courthouse :lol
For me it was not an issue since the family owns our own company so we can do what we want. During the jury selection process though many many people used work as an excuse out of jury duty. Basically you can't use work as an excuse out, but people basically up front told the judge and attorneys at selection that having to serve would "influence" them negatively during their duty. Those who didn't get off and had to stay on for the duration had lot of negativity towards it though of course.
Grand jury though can be different from state to state, the laws and roles change all the time. We had one sexual battery case brought to us which is unusual, but they had to do it because it was a case that happened back in the 70's and at the time of crime the grand jury took on such cases.