I don’t have numbers yet but I was analyzing my mini SS/FTP block. I did 30, 90, and then 45 minutes per week of SS/threshold on top of a lot of Z2. This block got cut short because we had to travel out of state unexpectedly. I took an active rest week and did hiking, walking, a little slow running, a lot of stretching and body weight exercises for a week.
Today I did 45 minutes of SS. It felt pretty easy - like my FTP has gone up 10-15 watts from the mini block.
I’m starting another mini block and will do even more time in zone and then I’ll test again in about a month. It will be kind of exciting if I can get a 10-15 watt bump every month for a while.