Obviously if you are an outlier at either end of the scale, you will know fairly quickly but what about those of us who have been running for a few years and there is no obvious bias?
Let’s say for example a guy runs 13ish/60 flat in the sprints and 17:30/36:30 in the distances (5 and 10k) or a woman that runs 15/70 and 20/42
Where does a person like that even go to make improvements providing they have done an equal amount of both speed and endurance work to get to that point?