Should I be emptying my hot water heater?

On a serious note, you should drain your water heater annually especially if you ever fill it with well water. Our old house was on a well and I would drain and flush our RV water heater annually and you'd be surprised how much sediment it would flush out. Not only can it degrade your WH performance, it can kill the electric element as well as erode your tank. Water heaters on a well last an average of 4-6 years if they don't get flushed. I never drained my house WH and after 5 years it eroded and leaked at the bottom. Had about 25lbs of sediment in the bottom when I rolled it out.

Never mind that a full RV water heater can burst in the winter if it freezes. That reason alone it should be drained as part of winterizing.