Originally Posted by TMonk

Yes the "all out" thing is a bit of a wild card. I just basically do a VO2 max interval first at a routine power (~115%).

As previously mentioned, the key letter in the FTP acronym if the first one IMO. I think the utility is mainly to establish training zones, not to understand what your power is at actual lactate threshold.

I'll bet that the 95% is an over-approximation for me. But knowing what I've learned anecdotally about myself as a rider, I can burn hotter at VO2-length efforts and recover quite quickly from being in the red, compared to what my (true) FTP would indicate. Both of those are more critical to most real world racing scenarios.