I have severely dry feet with horribly cracked heels, esp in the fall and winter months. I have been testing various remedies to see which one works best the past few years. My remedy tests include pure shea butter, olive oil and coconut oil, all applied externally and massaged into the bottom of the feet. I have also tried taking borage, fish and evening primrose oils (not altogether, one at a time).
Hands down, fastest and best results were applying coconut oil and then putting a cotton sock on. I do this twice at night, before or after dinner and then again before going to sleep and in the morning my feet are impressively softer with less indentation in the cracks. Not terribly fond of the coconut oil smell, but learning to live with it!