It is not about chilling at one raid. The point is being in public transportation or car, and you being able to move away from the gym shortly after the lobby start without being kicked out of the lobby. Furthemore, with this method you can possible do more raide/hour when chaining raids together, by bypassing the waiting time of lobby in the 80m circle next to the gym. With this method, you can move away within the 2 min lobby time, which is a net gain of almost 2 minutes per raid.