Interesting article, and I absolutely agree that 95% of 20min is not a one size fits all, but it’s also not that far off.
My realistic response is that people don’t even do the 20min test because it’s long and boring, so these longer tests would likely experience even greater amounts of people not doing them due to their complexity. Granted that I’m thinking about self coached athletes, that have rather busy schedules.
I’ll be honest that I rarely do FTP tests, but instead I keep a gauge on where my fitness is relative to my FTP based on Zwift racing results, and perceived difficulty of structured workouts. Based on those two things ( and looking at what my WKO4 model says) I will adjust my FTP accordingly. It’s lazy and not that structured, but I’ve found it to be effective for me, and it avoids all the hype and anxiety around a “test”. That’s not to say I never do them, I just use them sparingly, so I don’t get burned out on them.