Assuming no delays = There are no delays.

As in zero delays.

Using the most recent numbers available, you can expect a delay on Southwest about 20+% of the time. (My personal experience is even worse, and MDW is my home airport.)

I stand by my statement. "Assuming no delays" is a pretty big assumption these days.

It's probably best to assume you have a 20+% chance of a delay, and factor that into the equation.

Perhaps you feel differently. (I would never presume thay I know what you "obviously" feel.)