Often the limiting factors for an airline aren't the planes, but the humans to operate them. If the pilots aren't in the right place and available to fly, then an overnight to reset the positions of the planes does nothing. Nevermind the fact that resetting the network would in fact burn up flight time which seems to be in short supply.
Agreed, SWA canceled 2000 flights over the weekend, seems like they should enough rested crew to reset.
I did see in the Dallas Morning News that SWA had schedule the most flights today since the start of the Covid.
>Dallas-based Southwest planned more than 3,600 flights on Sunday, the most of any day since the COVID-19 pandemic began, but nearly one-third of those were canceled.