Just to add to the hr discussion, that is the one metric that is telling you how you are feeling that particular day. Following a plan blindly if your body is not reacting well to the conditions is an easy way to add more training stress than intended. How you can handle that depends on the line you’re already walking with stress balance.
There’s a reason people don’t get world records at elevation or in super high temps, because those conditions lower your abilities. So why wouldnt you think that the older prescribed workout is actually harder than prescribed if your hr is >= 10 beats higher than normal.
All that is a bit moot though as there are established protocols to calculate rTss and swim Tss. I was actually using excel to calculate swim tss and manually adding it to my calendar. I understand ml is a few steps away, but that simple feature has been asked for quite some time. That’s why i no longer use the calendar.
For running, grade adjusted pace isn’t perfect, but is an attempt to normalize runs over varying terrain. I mostly run on gravel though, so using pace gets tricky as my pace is also dictated by how recently they regraded the road. Fresh gravel us almost 20 seconds per mile slower than pavement, which is also why my garmin gives me very erratic vo2max numbers for my run.