I am typing this in April of 2020, at my desk in my home in Donald, OR, USA. It is a unique time because much of the country is not commuting, which has freed up the highways and byways. Those of us who are still commuting have found fewer restrictions from other people, and much more freedom to find a comfortable speed for us. There are still police officers pulling people over, so the sky is NOT the limit, but within the buffers of the legal system, there is space for every person to drive at a personally comfortable speed. My personal comfort speed is 70 miles per hour. At least on the Freeway, I am happy to drive 70mph all day long. In my state most posted freeway speeds are 55-65 mph, although a couple of years ago I found in the very rural areas, it does go up to 70 mph. I find when there is space, if I set the speedometer to 70 mph, it's fast enough that I feel efficient, but I do not fear getting a ticket, or being a hazard to others. obviously, I cannot drive that fast during a typical morning commute. But with lessened traffic 70 mph works. I don't like it for rural highways. Where the speed limit is typically 55 mph, sometimes 45. For that I don't like to go above 60 mph, and am happy to stay at 55. The primary reason is that there are a lot more unknowns on the rural roads. Deer, joggers, bicyclists and a whole lot more curves. 55 mph is plenty fine, and is also the speed limit mostly, which is convenient.
And that is about it. This question has been rolling around in my brain for a while, and it needed an outlet. I apologize to those of you who were expecting a metaphor. All I can say is that, if you really want to see one, you can build a metaphor in there. It might take some work, but it would totally be worth it. I am curious about what other people think of as "fast enough" and how the conclusions were reached. I know there are people out there who think "if there is empty space ahead, I can go faster." and that is fine, I do wonder why though. It is good to get that out of my head.