Unless you have a garage queen as shortspark does, the problem with trying to maintain your
SG layer indefinitely is that you will invariably pick up some wash swirls or more importantly some environmental fallout (tar, brake dust, sap, other stuff that sticks to the car) which you will want to get off on some periodic basis. Usually however you do this results in some compromising of the SG layer, so at a minimum you would want to reapply. With a real world daily-driver, you usually wind up having to do at least some minor polishing (which will remove your LSP) twice a year or so. This of course varies with your local environment, whether the car is garaged part of the day, etc.