When the schedule changes, the entire deck is shuffled. Past performance under the old schedule literally has no bearing on current performance. Any information you collected from the past schedule would be useless.
You can if you have enough information. Southwest has alot of seasonal routing where some of their nonstop service is only for a few months of the year.
One example is the sesttle-Nashville nonstop which operates roughly the summer to around October then in the other months its usually the same plane with a stop in stl, den, or mci.
Their data makes it harder.
Another problem that is unique to them is they have longer flight chains which compounds delays later in the chain. Other airlines operate a hub and spoke so they have spare planes to use if necessary...this limiting chain delays with flights.