What does “reusable” really mean?
Flying twice is a demonstration. Flying fifty times on the same schedule is a business.
Reusable is a word that has been stretched to cover everything from a refurbished airframe to a genuinely operational vehicle. We use it in one specific sense: the vehicle flies again without being taken apart.
The refurbishment trap
If a vehicle needs weeks of inspection and part replacement between flights, it is technically reusable and practically expendable. The cost and the schedule are dominated by the work between flights, not the flight itself.
The goal is an inspection you can do with the vehicle still on the pad.
Orbiter is rated for fifty flights per airframe with a scheduled inspection every fifth flight. Atlas is close behind. The number that matters is not how many times a vehicle can fly. It is how little has to happen before it flies again.