Envoy publishes lines with specified trips/reserve days and days off and the pilots bid on them. Most people use the Quickbids app but you can also bid manually in SABRE/FOS. There is a trip trading system after preliminary bid awards. You can request to drop days and it is approved when there is adequate staffing in your base and position. Reserves can request to swap or drop reserve days. We're over staffed rignt now in anticipation of aircraft deliveries soon, so flexibility will be reduced when we get more planes. I'm sure scheduling is much better at the legacies but it's very civilized for a regional.