I think a big part of the motivation to have many launches within hours is because in order for Starship to deliver anything beyond low earth orbit it will need refueling by many other Starships acting as tankers.

This means that for one mission to the Moon for example you might need >10 Starships to launch, and it's better to have them closer together so that you don't have fuel in space being heated by the sun for days.

It remains to be seen if they will actually reuse a booster on the same day, but there is a use case for it.