I just listened to the AACC podcast that covered this exact question! They cover it in episode #144 at 48:45. I recommend you go listen there, but if you want to hear my regurgitation of it, here you go:
The short answer appears to be that holding a very high power for a short period of time won’t provide the type of physiological adaption that will allow you to hold that power for a long time; it will just make you able to hold a very high power for a very short time.
If you want to hold a high power for a long time the best way to train that adaptation is to hold incrementally increasing levels of power for incrementally longer periods of time.
They use the example of weight training. If you want to bench press 500 pounds you don’t go into the gym and try to lift 500 pounds over and over again until you’re strong enough to move it. You start with a weight you can lift and incrementally increase it until you reach 500 pounds.
But the best bet is to just listen to them explain it…