As I understand it, that is a training pattern for med or high maturity athletes. What I found interesting about the off-the-shelf FasCat plans is that there is a tradeoff - in general vs TR (or Cusick’s fatigue resistance ‘go long’) the mid-week workouts have fewer intervals and less time-in-zone. For example during the 2nd block of base (SS2 example on FC website) the mid-week block is Tuesday 3x15 Sweet Spot, Wednesday 3x12 Tempo, Thur endurance/z2. When I did that last spring, it just worked. And I was STILL able to go out once a month and nail a 1x50 or 1x70 just below threshold, which is how I built out time-to-exhaustion to 60+ minutes in 2017 (first Saturday of Jan/Feb/Mar/Apr 2017 was 60+ threshold effort).
Perhaps not completely fair characterization, but the sweet spot progression thread seemed to have a lot of (younger) people slamming SS TIZ above 60 minutes, twice a week. That simply requires too much recovery at my age, when done weekly. I believe the minimum effective dose is far less, or you are better served by going out for a mid-week drop ride.
My observation of FasCat plans is this tradeoff on reducing the number of intervals / TIZ mid-week, thereby increasing load via back-to-back intervals Tue/Wed, and then a big weekend. I have enough data to say that basic pattern works for me. It might not work for everyone. My coach manipulated that basic template and personalized even more (I was doing gym work too), and it shows in my power curve and hard efforts.
Those mid-week back-to-back interval days made me stronger before TR in 2016-2017 (when I was your age), and again after TR 2020-2021. I think Frank Overton calls it fatigue dependent design, or designing a plan to go with the grain of fatigue. Instead of going longer and longer on the intervals, he keeps them manageable which allows me to throw down on the weekends, and throw down a long ~60 minute interval at least once a month. In turn that increases fatigue resistance (TTE) while not increasing recovery required and still allowing me to do 3 weeks on and 1 week “regeneration” and I say regen week because the FC plans lower volume but keep intensity.
Another n=1… I found 3:1 with regeneration week (with some intensity) works better for me versus TR’s SSB of 5:1 and recovery week is all z2. Keep in mind this is an off-the-shelf plan from a long-time coach that has accumulated a lot of direct feedback from 35+ year old athletes that work and have families. And he has a coaching staff. My coach has a lot of athletes, and its still surprising how well he knows me. I’m sure he keeps notes and reviews before our monthly 1-1 and weekly workout feedback.
Where it got interesting for me with FC 16 week plan was when I skipped some of the long days on the weekends in SS1 and SS2 (done during early days of pandemic). Then I started SS3 and I clearly wasn’t ready, so I repeated SS2 and then SS3 produced excellent results.
A lot of this comes down to experimenting and finding what works. I still keep an open mind and try different things, in fact this is a discussion topic at every month’s 1-1 with my coach.
Hope that is useful food for thought, and helps you or someone else.