PBS will make that completely impossible - ask anyone at Delta. They've got PBS as contractually in check as any major does, and they'll still work the other 3 weeks of the month in a month they have one week of vacation. Might be less for those senior in a wide-body category with high credit 7-12 day trips.

PBS should be avoided at all costs, unless you want to be awarded more days of work per month for the same amount of pay.