Possibly a bit of a tangent but one thing I do find interesting is simply looking at power vs considering HR/breathing rate. My understanding of VO2 Max training is that the objective is to accumulate time in a state of maximal oxygen uptake, as that’s what stimulates the training adaptation (this thread covers it quite well - Time Accumulated at VO2 Max (or +90% MaxHR) - Training - TrainerRoad). On some hard group rides and races there will be sustained periods of time where my power is spiking all over the place and certainly not structured, but based on my HR and breathing (=gasping) I’m accumulating a lot of time in a state of maximal oxygen uptake.
E.g. in a recent 1 hour VO2 max session on TR I spent 20 minutes in the VO2 Max power zone (Gendarme+1 - 20 x 1 minute intervals) but only 12 minutes with HR above 90%. . In a recent 1 hour crit I spent 18 minutes in the VO2 and Anaerobic power zones but over 30 minutes with HR >90%. Crit also accumulated some Threshold and Sweetspot time (though not much! Never managed to get a break to stick long enough to settle into steady high power) but I still suspect that an analysis of that crit based purely on power (time in zone, TSS, NP, etc) wouldn’t fully capture the training benefit.