Agreed with the caveat that it should probably be some significant fraction of the estimated reading time. That's just an average, and some people read far more quickly, while some people of course read more slowly.
I'm in the same position as you in terms of running a publication for the love of it. I edit and publish 3 to 4 stories per day, 7 days per week, and I read many more stories than that every day, from other publications and from writers who are not in publications.
I find that as I read, often with an unconsciously unintended editorial eye, I finished stories in about half the time that Medium estimates as the reading time, ... and I'm not skimming. I guess I'm just on the faster end of the average.
Just kicking in in case Scott is listening. I like your idea.