At the Fractional that I work at we are 7 on 7 off so a one week vacation turns into 3 weeks off. Also twice a year (more with the approval of the Chief Pilot) we can move a rotation up to 7 days which will give you 2 more consecutive weeks off. At the 121 I previously worked at the best we could do was to turn one week of vacation into two. But then you had to work every weekend the remainder of the month.