You have some good points. I have noticed different inconsistencies at times but have never taken any thought to investigating. Even this morning I have noticed a new story I published last night has views and fans, but no reads, and the read time recorded is mere seconds.

I do wonder if there might be any contributing factors, such as a particular internet browser which does not work with Medium calculating read time very well. Maybe a change in an update they made to the browser. Or even just a difference between the Medium App and website.