Curt - at the Sanctuary we use a hard finish (some sort of varnish/stain) on our front doors, which needs to be re-done every few years.  We inspect all doors every Spring (with our contractor) and then make a decision as to which doors need recoating.  They face all different directions, and some are covered while others are not, so some need it more often than others.  We use Old World Painting out of Breckenridge.  We've never had to remove doors, so not sure how we would do that.  We occasionally have some minor repairs, i.e. crack sealing, but that is done with the door in place.