What's the scenario where you would want to do that? I understand there's a (theoretical?) scenario where you want to minimise latency between screen rendering

What's the scenario where you would want to do that? I understand there's a (theoretical?) scenario where you want to minimise latency between screen rendering (or input handling?) and presentation. But if you use double buffering, which a while loop that block until the frame is presented, then the CPU will sit idle while the GPU is doing it's work. Instead of preparing the next frame after that - which may result in the CPU preparing the next screen too late if the scene complexity is fluctuating.