Veebyes wrote:
That is not what the OP asked about. He asked about reservations while in transit which generally are totally unecessary. Even during a holiday weekend drive up spots can be found away from the destination areas before having to resort to Walmart.
For me that tends to be generalized and cannot easily be applied nationwide. It varies considerably depending on region and time of year (not just holidays). For instance, much of the California coastal regions is difficult to get a spot simply by showing up throughout the summer months and much of the spring, in total a large portion of the year. Elsewhere many areas of the USA are rarely busy even on holidays. It really varies depending on where you are traveling. For me the last thing I want to do is have to hunt for a spot during the afternoon when I'm tired after driving.