It’s not complicated and it’s not a faff.
The only time you really need to know an average is when you do the field trial thing, and that’s only once at the start. You just do two 8 min intervals as hard as you can sustain and take the highest average of the two. You then use that figure to work out the ranges (there are about 5 I think) that you then use in subsequent workouts.
When you do the intervals in the program you just try and keep your current power/hr within the range you calculated for that specific interval. It’s not complicated, though they are hard workouts and I found writing it down clearly before the workout made it a lot easier to follow.
Agree with the comment of using the program to train for a specific event at the end of the 3 month program. If you just want something to follow year round then this probably isn’t the right book. Though principles are worth knowing.
Also regarding the “supplements” comment, not quite sure what flap_jack was alluding to. The only thing in this book is about being properly fuelled for the workouts. There’s guidance as to how much carbs to take for length of workout, that sort of thing. No mention of any special beef marinades!