I'm only a casual fan and I don't follow every change in the rules each year.
But decades ago I seem to remember that in any given game, NFL or college, the measuring chains would be brought out onto the field at least 2 or 3 times to check whether a first down had been made or not.
But watching several games this season I believe I've only seen the measuring chains brought out once (last week in one of the wildcard playoff games).
Was there a rule change at some point that reduced the need for measuring with the chains? If not, what's going on?