Glucose Testing Question

I have my glucose test next week and I'm just wondering if I fail and have to go back for the three hour test my doctor said I have to stay at the drs office the entire 3 hours while I wait - do all drs make you sit there for the entire three hours - or do some let you leave and come back every hour for the blood draw- I just can't imagine spending three hours in this tiny ass office without any internet connection or cell reception lol- I'll go nuts!