I do recommend counting cars you overtake and those that over take you.

Turns out I was overtaking 10 cars for every car that overtook me. I've calmed down since then as it really put it in context how fast I was driving.

I do what Mattmanser does on long highways with not too much traffic as a proxy of me going with the flow. I discount merging vehicles, it’s harder to take into account exiting vehicles but with exits being rare that works ok. Also: waze

Kind of like Isaac Asimov on writing. I can't find it online, but he once said that he writes better than anyone who writes faster, and faster than anyone who writes better.