Actually you are wasting 50 minutes in this scenario as you could have used the time not driving yourself to do something productive/enjoyable.

Sure but it that is the best case. In my own experience, traffic can impact those numbers substantially. And just some bad luck with traffic signals can eliminate most of those savings as the slow/fast cars tend to get synchronized.

Just the other day I was driving down the narrow roads of a nearby hill and there is a section with single lanes with lots of traffic moving at 35 mph. One lady comes weaving down the traffic on both sides to get in front of the crowd with a net savings until when the lanes opened up of 30 seconds. So much risk to everyone for what little benefit.

Unless I was under some big time crunch, I would gladly trade that amount of time for the luxury of being driven on a long roadtrip.