The time post training when you take an ‘RPE’ is critical - subjective scores for metabolic fatigue are greatest immediately post training, but will fade as time passes.
An ‘RPE’ taken after a short neurally demanding fatigue is often worthless - in fact misleading in many instances.
IMO the question is this - Is it worth while at all assessing Rate of Exertion or is it best ask the athlete to assess their current state?
They are not the same thing.
Also, intra-set RPE’s are a another completely different method of monitoring, but perhaps I shouldn’t throw that into the mix!
Then there is the learning effect of using RPE’s …