Yeah, FTP building is a great place to start really as it lifts all your zones. Anything above threshold is quite prone to ‘use it or lose it’ which is why plans that utilise Vo2 max intervals are handy if you need to keep hold of some top end.
The flip side is, short, hard stuff is quick to improve and equally quick to plateau so if you are training a long way in advance then the time may be better spent working on endurance this time of year as the intensity also increases fatigue.
In the TR podcast episode from the Riprow thread, Lee McCormack talks about spirals of learning in relation to bike skills whereby you work on specific skills in turn- constantly ramping up the level.
Well, really, that’s the same as the theory behind Friel (TR plans are blatantly ripped off from Friel with Coach Chads twist) and any other periodised training plan.
By going Base, Build, Speciality, rest, Base, Build, Specialty, rest etc etc you should continually spiral your fitness upwards.
The trouble with trying to keep your entire game sharp all the time is that you never really maximise your potential so everything blends into a dull beige of performance with random peaks that may or may not coincide with a ride you care about.