If you have extremely low blood sugar levels, how many times are you supposed to test them in a day?

My friend has Very low blood sugar levels and today she checked them about 10am and then again about 10:45 am, i'm just wondering does she need to be doing it that often? She says she has to be at 6 but what are most people really meant to be at-isn't it between 3 and 6. She keeps saying she feels like she's hypoing(sorry don't know how to spell it) but i think she's faking it cause there are no signs of a hypo.