It also depends on the type of surfaces you walk on as well. Concrete not so great because the concrete is not "real" and disconnects you from the earth.

Not to get too Woo-woo on you but you can look into articles regarding "earthing" or as I just call it, walking barefoot.

Grass is great, also anywhere that is 100% natural or also a place that is a bit uneven as well, so you can hit all those points in your feet.

I love walking barefoot and how it feels after. I currently live in Bali, Indonesia and try to do it as much as possible.