3-1-3 split shift, Common? Uncommon?

I have a friend who I graduated from nursing school with, who has told me recently that she is able to work 3-1-3 split shift at her job. Here is her words exactly "I work 3 days, off 1 day, work 3 more, then off 7 days, repeat." I would love to be able to work shifts like this. My question is, is this easy to accomplish? Is it common or uncommon? How hard is it to get a schedule like this? I have only been a nurse for a year, and have just worked at one location and facility so far, so I'm not sure how flexible other facilities and hospitals are with scheduling. Any advice or information would be appreciated. : )