I commute on the west coast. There was a guy on my Monday flights more than half the time. We thought about using a Companion Pass to cut costs but for two reasons we never did it:
1. Coordinating travel with someone other than a family member is a lot of work. Plans change and the companion passenger would need a backup reservation, which is more work to set those up, cancel them, and re-use the funds before they expire. (This is easier with the new points system, but Southwest officially prohibits duplicate reservations.)
2. In the early years we earned a free fight after 4 round trips, so we were effectively already flying free. In recent years we each needed to have 50 paid flights to reach A-List Preferred Level, so the companion would lose out on that.
Just paying for our own tickets was much, much simpler.