Truly going by feel is the most important thing. I've seen some of the highest-level pros with a standard watch instead of a GPS.
Men's world records - 1000m to 3000m all from late 90s.
Rojo 2:23 Marathon - Timex Triathlon Classic 30 Watch
Wejo 28:06 10k - Timex Triathlon Classic 30 Watch
Jon Gault 14:25 5k - Suunto Digital Fastime RW3 - Blue
Easy is easy, moderate is moderate, effort is the most important thing. Go to the track once a week, or a measured loop - hit the workout to see where you're at, then run easy by feel to recover, log it all in a book, do it again. Mileage is a biproduct of the work that actually needs to be done... None of this silly Strava mileage tracking, data selling, social media distractions to getting in your way.
Time the run, log the time or miles, get the effort, and keep it rolling. Somedays are faster naturally, and some days are slower - the body decides, not the watch.
DISCUS