Oh, I think Norm hit on something. As a group over the years, we adopted very few sets of rules, finding one we liked and then sticking with it. So, we didn’t have to learn multiple rules for multiple periods. For example, we used 10 sets of miniatures rules for our eight core gaming periods, spanning 36 years. The newest one of those is 17 years old and is homebrew.
We bought and read lots of rules over the years, but didn’t play the majority of them, or played one or two games and went back to our regular set. Not having to learn many new sets would explain the lack of needing to refer to them often.