I think Tinman's over-arching theme is to keep the ball rolling and to never apply more stress than your body can absorb. Stress definitely comes in the form of running. It is trauma to the body even if we enjoy doing it.
Stress also comes with careers, family, kids and potential lack of sleep from being an adult and worry about "adult" things.
If one rep is your starting point, start there. I think when Tom actually did this training he said he was a 18:30 5k runner and began his 3-day rotations at 3 miles per day and worked up to 5 miles per day as he become more fit. He started with continuous 3-mile runs at the following efforts - still "today's" 5k pace:
Easy = 5k pace + 2 - 2:30 / mile
Medium - 5k pace + 1:15 / mile
Somewhat hard = 5k pace + 45 - 50 sec / mile
These were the average times for each of the runs, noting that he would start each run easier than the bottom end of the ranges but finish a little faster than the top end of the ranges. Doing so made those paces the average pace for the run, if you will.
I do think the strides and faster, short bursts near the end are exceptionally important to include but it sounds like you don't have a problem with those.