A little over two years ago, I was an avid triathlete with an FTP of approximately 270. In the intervening two years I did virtually nothing except gain weight. On November 10 of this year, I rode the ramp test, and determined that my new FTP was 165. Thereafter, I completed the Sweet Spot Base Mid-Volume I Plan (although I cut a few rides short because I needed to build up to the volume). Thereafter, my FTP increased to 185. Now I am midway through another base plan, and suspect that at the end my FTP will be somewhere in the low 200s. At this early early juncture in my return, should I continue to ride base plan after base plan, or should I go through a build plan even though I have no events scheduled? If it helps, I don’t think that I will attempt another triathlon or biking event until sometime in 2020. My goal is really to improve my overall fitness.
I would absolutely follow the plan progression and start a build phase after you complete Sweet Spot Base II, you’ll likely see significant improvements from build and once completed you may wish to return to a block of sweet spot depending how you feel, what your outside riding looks like etc.
Who knows, you might even find an event that interests you this year!