I take my brand new Brooks saddle(s) and lay it out in the sun, once it is warm it gets a very heavy coat of Proofide on the underside and a lighter coat on the topside, set it back in the sun for a couple of hours, wipe the excess off the top and ride. I use fenders on my bikes so the underside stays well protected. I "might" give it a retreat once every 5 years or so depending on the condition of the saddle.

Aaron