Hey Curious1. I recently spoke with sirpoc84 about the TSS score range and his thoughts. He and I have both been seeing a range of about 75-85 TSS, but my workouts included 3.25 miles of easy running (1.75 warmup and 1.5 cool-down), so too much of the load was coming from easy running. I'm going to be doing 1.25 miles for warmup and 1 mile for cool-down moving forward, and adjust interval time/distance in order to find the combo that puts me in that 75-85 TSS per workout range.
I just ran a 5k trial yesterday and PR'd, so I'll be working with updated and faster paces, which is why I want to start with 30 minutes of intervals each workout and hopefully move toward 36 minutes per workout. I figure if my fitness improves as I use my new paces, I'll naturally need to add reps, time, or distance in order to achieve a similar TSS score for the same pace. I'd started to run faster paces this past week due to not hitting the right % of threshold HR, which prompted me to do a 5k trial. But I will never again increase the pace without getting a new 5k trial PR, and will instead add time, distance, or reps.
I'm gonna start sticking to paces based on threshold pace from a VDOT or other Daniels-style calculator instead of max HR during an interval rep. So, I'll be using the 75-85 TSS score to assess whether I'm going too easy or too hard. My HR just seems to go all over the place to trust it as the primary metric, but I'll certainly be checking it at the end of reps just to be sure I'm not going over the HR threshold. But I really am starting to believe that using a recent time trial to calculate threshold pace, using updated paces based on that time trial, monitoring TSS, and possibly grabbing a lactate meter will be the best way forward. In lieu of a lactate meter, I'll rely more on recent trial or race PR, updated paces, and 75-85 TSS as my guiding light. I'm also hoping that if I hit 85 TSS one day, that I stay below that on the other two days to get a 3-workout average closer to 75-80 TSS.
I know, I went way off topic, but I hope some of what I've said here helps.