If you add the massive Starship+SuperHeavy in for scale, it looks even smaller.
https://twitter.com/Caspar_Stanley/status/136834862870895001...
https://twitter.com/Caspar_Stanley/status/136834862870895001...
So I don't think this can be a high flight rate facility.
Basically, I think they want to keep up the testing cadence without having to delay things due to maintenance. They say in one of the applications that there will be no more than about 10-12 orbital launches from Boca Chica per year.