I’ve added my outdoor mountain bike rides (no power meter, but have HRM) to the TR calendar.
For some of them, I’ve calculated my hrTSS using Training Peaks, and I’ve found that hrTSS can give some interesting/wierd results. For example, I did a 6hr race in August where TP calculated my hrTSS as 602 - which is “too high” i.e. there is no way I was riding at threshold power for 6 hrs.
For the 2017 LT100, TP calculated my hrTSS as 701, which is closer than the above to what I think is a “right” TSS, but still maybe a little high as this would have me at an IF of 0.72 for the duration of the LT100.
hrTSS is a useful metric to have, but for me, at least, I need to interpret it thoughtfully for it to be helpful.