I can see that. My feet take a few days of careful husbanding before they develop the callouses for a new pair of sandals, and there's gonna be some sore spots. It helps to stick a bandaid over the sore spots to give them a chance to toughen up.

I can well imagine that some people might take longer or develop blisters more easily, preventing the skin from getting to that point. Dry skin is a good hypothesis.

Socks are a totally decent option. If it's not going to happen, don't try to force it. /nod