I was never suggesting that starting a render run at the last possible second to ensure the frame renders in time to be scanned out was actually a viable approach. Only that it was theoretically optimal.

But hardware changeout would not meaningfully affect people attempting such an approach, because it would obviously be based on actually timing how long a render pass took, adding a small buffer margin, and using that as the timing.

Which does mostly work, except when there is a rapid change in render time, like due to switching on a giant particle effect changing the camera from pointing at the ground to pointing out at the open world, getting close enough to an complex object to swap from a lower LOD mesh to a higher one, etc. These would likely cause meaningful lag spikes as the system tries to adapt.