If you live in an area that has hard water, you stand the chance of closing the valve on a piece of calcium. Then you would have a leaking valve and need a plumbing repair. If you dont have hard water, maybe draining would serve no purpose. Here in San Antonio (hard water), I used to recommend that people never drain the heater, just replace it every eight to twelve years when the calcium builds up. I just realized, I dont know enough to answer your question, sorry.