FTP testing protocol for Masters - Indoors and Outdoors?

With all the top coaches weighing in on the topic for pros as of late. What’s actually useful for masters athlete’s?

I typically don’t test regularly anymore. After 20+ years, I have come to know where I am at pretty well. I don’s stop training year around but I do back off on volume and intensity over the winter in favor of strength training and alternative cardio (rowing, running, hiking) but still keep the bike cardio a priority.

So, getting back into a goal focused season:

  • 20min test (which is what I have always done)
  • 2x5min test avg those efforts x .75
  • Ramp test

My question is: What is the best protocol for indoor and outdoor?
I find it hard to maintain focus for 20min indoors (motivation maybe) Outdoors, not problem.

My numbers if it matters (I am 47) for the sake of the discussion:

  • Winter FTP is unusually 280-290w
  • Spring after an endurance block 300-305w
  • In season 315-320+