Indeed.

To give some idea of the potential variability in this approach: years ago I tested two subjects who, despite having sustainable powers of <300 W, made it to 500 W during incremental exercise tests to measure their VO2max.

One was a collegiate runner-turned-duathlete, who had sub 15 min 5 km PB despite weighing 75 kg or so (IOW, more of a mesomorph than an ectomorph).

The other was an even stockier fellow who mostly trained by lifting weights, but also did some of what is now known as 'cardio.' Perhaps more importantly, he had grown up surfing in So Cal, so had spent a lot of time paddling/swimming in his teens.

On the flip side, when I was young I could only make it to 425 W or so during such a test, but could sustain ~350 W (i.e., 82%) during TTs.

That said, most people will fall within the 72-77% range put forth years and years ago by RST Coaching...as with Hunter's 95% of 20 min power rule-of-thumb, though, there are exceptions (and for precisely the same reason, i.e., resistance to fatigue during supra-steady-state exercise can and does vary between individuals).