The problem of weather delays propagating across the entire system affects all airlines. One additional cause of cascading delays that's unique to WN is its short scheduled turn time. They routinely schedule aircraft to depart 45 minutes after arrival. When load factors were lower years ago this was reasonable, especially with WN's industry-leading turn efficiency. But with loads approaching 100% on many flights today it's hopelessly optimistic. Seating passengers after the first ~85% of seats are taken is much slower as overhead bins fill up requiring carry-ons to be checked and passengers take longer to choose from the remaining seats.