50'/round (for a 10 second round) is about right for a normal walk. Depending on age and how much of a hurry people are in, a brisk walk is not uncommon, and that's modeled pretty well by 1.5x BMR. A brisk walk uses more energy but if time is more valuable to you than energy, you'll probably walk briskly.
E.g. https://en.wikipedia.org/wiki/Preferred_walking_speed gives 4.6 ft/sec as typical, so that's 46' per (10 second) round.
More here https://en.wikipedia.org/wiki/Walking