I tried Xert in 2017 and used it for a 2nd peak in November of that year. Just cherry picked some workouts. Dropped it after a year, and tried it again this year. From the past I knew that it relies on breakthrough efforts, and without enough of those (e.g. during base 1, 2, 3) you want to set signature stuff to no decay. Its a little confusing and I sent a support ticket providing expected FTP at key points in past season, based on field tests and WKO. My terminology may be wrong, so apologies, they promptly locked the signature to a workout in August and set to no decay. I have a coach and am just shadowing for analysis, like in 2017 the threshold and lower threshold and high intensity energy have been pretty accurate. But I still have no clue how to use it to program weekly and blocks of training.