Depends on what the Plan calls for.
That run, was trying to keep to 16/km/hr - and just see what the heart does.
Other runs, esp recovery runs, are to keep the HR down.
Runs that are for base training, are to keep the HR UNDER La+ at all times (a couple of sec here and there due to road conditions…) But yeah, there are deff runs that are done watching the HR instead of speed or whatever else. This makes training easier to recover from, and allows for more volume.
Re- lung thing - I have had the burning throat thing from cold - i think i have had the crampy lung thing before, but - not for such a long period of time (in terms of time eg months or yrs, and in terms of time eg During a 1hr run, or Time Trial - if it was during a normal training run, i would have stopped for a minute or two…)
Sunday -
21min easy recovery run or 3.8km
then 35min of Running Circuits - 4.2km
Total for the week - 4hrs 11min
2 x time trails
2 x days off