I have the same problem. I think others have as well. What I'm doing is getting a pedicure every two weeks. I consider it almost medical at this point. I also found a really good cream by Origins called "Reinventing the Heel." Might be hard to get, as you have to be near an Origins store. Also, really super good is finding a cream with Urea in it. I got one at the podiatrist office with 40% urea and this is almost toooo much. You put a cream with urea in it on any callouses and it truly helps a lot. If I use the urea cream a few times a week and the Origins cream almost every day and get the pedicure twice a month, I'm good. But, it DOES seem like a lot of work and I often forget or mess up. I live in a warm climate, so we wear lots of sandals or open toe shoes. UGH! I just bought a new cream for my hands that I heard is very good: L'Occitane. I put off getting it for a few years due to the cost...but I think it might help. I do think this dryness is rather common.
When mime do this I sleep in socks and gloves which my husband finds very funny. I put Vicks salve or vit e lotion on first. I would speak with your doctor as some people have trouble with the menthol in the salve.