So I want to point out two more things. Coach Jack is more like a tool for building plans, if there are some specific sequences you would love to see and they make sense to us we can add more custom sequences, you can give the idea and I can have Andrea review and make suggestions as to how he would design them. Some of the ones that are there, came from user requests.
We would also argue their is confusion as to what is required to get faster, and for example we would say maximizing CTL/TSS was proven by Dr Seiler (polarized training) is not a requirement. He does like really hard VO2 max sessions though 
One point to address is there is always high degree of individuality and where you are today. If you are doing 4X8’s now then the chances of a 1 minute threshold causing adaption in you is low/zero
Generally CJ can work for people and if you try the serious Italian with it’s SFR or our the custom Dynamic Force sequences you might see some new adaptions you never expected. I love these workouts and they are not popular today, but wow
https://forums.trainerday.com/t/sfr-italian-plan-low-rpm-workout
Here is a post from one of our users that saw great success with Jack’s plan
https://forums.trainerday.com/t/my-experience-with-trainer-day-so-far/