March 2017 is when I did 8-min overpaced effort, 20-min overpaced effort, and 50-70 minute effort. They all aligned well enough. Right now the WKO model has 20-min at 95% aerobic / 5% glycolytic. And 8-min at 89% aerobic and 11% glycolytic. When the WKO is well fed, over 5 years I see some movement in the 8-min aerobic/gylcolytic % split but the 20-min is pretty stable at 95% aerobic which for me, makes 95% of a 20-min test a good estimate of what I can do on a long TT effort.
Yeah I just go out and do some longer efforts. In my world, pushing freestyle sweet spot out to 2 hours has a big impact on what I can do in the 5+ hour range. I’ve never tried predicting those long efforts.