I re-season about once a year if needed but my grandpa never did. He didn't wash his pans with soap or water ever and he used them daily for at least 40 years that I know of. One of my pans is one I inherited from him and I did have to re-season it because it had been left outside for about 5 yrs after he died. I got it back to being nice and shiny black. I hope our method works for your pans, I'd love to know how it goes.