I have been pondering this one for a long time. At what point is your easy pace your marathon pace?
To give a little bit of perspective, a beginning runner who runs 40 mpw in preparing for a marathon will likely run slower in the marathon than they do for an “easy” 5 mile run, while an elite runner whose marathon pace is 5:00m/mile likely runs slower than that for easy runs.
What is the equivalence point? When is your easy pace your marathon pace? Is it a weekly mileage? Is it a marathon PR?