The CrO paste is also used to refresh the edge when your razor begins to tug. I use it thus when that happens. When the CrO paste no longer refreshes the blade sufficiently it's time for a barber's hone or something like a Norton 4K/8K followed by the CrO. Experience will let you know when to do this. Unless you damage your edge (like dinging it against the faucet, like all of us has at some point), you will not need to put a new edge on the razor for a very long time.