Just posted my review. I can happily report about a 37% increase in my FTP following the 18 week SS plan. That is from a near-sedentary condition of course after years off the bike, so that will not be most active cyclists’ experience, but if you are a beginner or coming back from a (very) long layoff from fitness, you can expect some exciting gains.
I went from full sedentary and significantly overweight to a program of 3 days kettlebell and 3 days of Zwift per week, and did that for around 2 months before I went all bike with the 18 week SS basic plan. Starting FTP test was 164, now after the plan it is 225. So a 61 watt gain or 37%. I followed the plan pretty religiously but I did update my FTP regularly by bumping it up in the spreadsheet when I could see my heart rate had declined 3-5 bpm vs an expected power output. The fact I only did Zwift and only in erg mode, I could reliably watch my HR for consistent changes, then change my numbers and verify that future workouts in fact matched up HR to power. Also I did insert extra rest days when I was totally smoked, but they were rare and I often found that I recovered enough from that extra rest day that I could eliminate an upcoming official rest day. I also actively added zone 2 time to the basic plan starting after six weeks or so.
Two thumbs up for Fascat and I will be progressing with more of their programs!