The 4 day trips are more or less the same across all bases, both 737 and 320. Nothing special about PHL in that regard. A mix of 1-3 legs per day across the 4 days. Some have a built in 30+ hour layover on day 3 so you get that day “off” in a random city. LAX trips tend to start with a red eye on day 1, east coast trips can end in a red eye on day 3/4. The company “optimizer” (sodomizer?) builds those trips to get as close to 21 hours of pay/credit (5.15x4) as possible so as to minimize “soft time”. The company would rather build a trip to exceed the 21 hours via hard time flying than drastically under fly and get paid a ton of soft time to bring you up to 21. My Delta buddies say the same thing.

4 days that are commutable on both ends definitely exist, and obviously they go senior. Commutable on one end behind that, and non-commutable go junior. Everyone agrees that there needs to be more commutable 4 days, but then if all of them were then someone else would b—— and moan about something they don’t like about them.

I don’t think anyone is gonna take the time and effort to do some sort of forensic analysis of historical PHL 4 days and sort them by commutable and seniority. If you have access to the APA TASC and scheduling products, you could probably do that project though.