I used a HRM for three years and found it puzzling. I consistently found myself running out of “zone.”
Well, if you’re consistently out of your zone, then you’re not using the monitor correctly. Especially in the early stages of using the monitor, you have to keep those easy runs very easy. I’d say within 8-12 weeks you’ll be running 60+ seconds per mile faster with the same HR.
My max HR was 195 and I had real trouble running less than 140 bpm. And averaged 167bpm for a marathon. The HRM was most useful dialing in my LT pace and late in races, like the marathon, it was my “watchdog” making sure my HR didn’t drop under 160.
My max HR is also around 195 and the lowest I go is 140-145. I’d probably average 170-175 for a marathon, 167 seems a little low. Also, if I wear my HRM for a race, it’s strictly for post-race info. I never look at it to provide feedback on pacing during the race, definitely not “late in races”.
I’m not sure what you mean about “making sure my HR didn’t drop under 160”. If you’re averaging 167 for a race, why would you be dropping below 160? You should be cranking it up at the end.