Since I only perform this operation rarely, I'm a bit unclear about the particulars of all this...
Definitions
Pair: Establishes a connection between drone and controller so they recognize each other and function in normal operations.
Bind: Establish a relationship between the Remote Controller and a DJI user account, associating an owner with the drone.
Out of the box, the drone can be paired with a compatible RC, and flown up to 5 times before being required to be bound to a DJI account. Also, I believe there are very restrictive height and distance limits in this situation, but that's a vague recollection.
Unclear: After first binding, can the drone be simply paired again with a different RC, without binding, subject again to the 5 flight limit until bound to a DJI account?
Binding requires an internet connection. This may not be available where a pilot has to change drones for some reason (crash, spare), and it's not practical to carry a bunch of controllers.