what about applying d3 topically to the private area in men? is it useful? d3 in extra virgin olive oilI live in the NorthEast US, and I get sun from about May to September, and do not use my Sperti, but the rest of the year I use it three times/week. This is pretty much an arbitrary decision since I do not test for D. I am a believer that the storage test for D does not reflect a person's true D status, anyway. It is like checking your fuel line in a car to see how much gas you have in the tank. The serum levels are not the place to test for a fat soluble hormone, which may be replete in tissue, but not in serum. Anyway, I do not think the Sperti needs to be used everyday, but it can be if desired.