Maybe take a look at this:
Breakthroughs are something you have to do yourself. You might want to do one or two now to get your signature dialed in. What works best for you is a bit of a matter of taste.
- Racing (Zwift, RGT, real) or something similar (Strava KOM/QOM?) works for some indoors or outdoors.
- Breakthrough workouts from the library work for some, everyone has their favorite.
- There are sometimes Breakthrough Sessions that usually use “A Paint that I’m used to” a Ronnestad workout in slope mode.
Generally it is not a bad idea to experiment and do several different kinds. Not all at once of course, only do them when you feel fresh and motivated.
They ‘look’ pretty different but generally something that draws down MPA slowly and has a bit of a sprint involved at some point is supposed to be best to get all 3 values right.
A well dialed in signature is very important because the workouts rely on the data. But once it is correct it keeps pretty well if you stay on “no decay” and if you like doing Breakthroughs every few weeks then it is best to switch back to “optimal decay”.