At Frontier you can pick up on your days off, and you can “aggressive” pickup while on reserve. Aggressive pickup allows you to basically bid for an open time trip if it’s available the day before your reserve assignment.

You can juice your credit if you’re picking up on your days off this way, or if you’re looking for flying while consolidating.

It also removes you from having to pick up the phone (IIRC) if you want to sleep in or have a little more of a predictable schedule.