I go through base-build-specialty twice a year (for road and CX, respectively) with a ~two week gap in the middle where I do a bunch of outdoor volume (around 15-20h / week) with no specific interval training and no racing. It’s at the end of that ‘just riding around’ block that I test the highest using a variety of methods (8’x2, 20’, BSXinsight while it still worked, and now ramp). I’ve not seen more than a 2% improvement after build phase and sometimes seen a drop.
However, my race results do not correlate with FTP. In fact, they peak with late specialty phase. My conclusions are that (1) I’m already at my genetic limit as far as FTP (2) FTP calculations are good for setting the interval intensities in TR and (3) race performance is so much more than just a number measured on a trainer.