I empty mine as part of the winterization and then rinse it out with a wand during de winterization. If by some chance I haven't had the coach out for a month then I may drain it to get stagnant water out of tank. Actually I pay more attention to getting stagnant water out of the outdoor shower than I do the water heater.
The other time I will drain the water heater is when I am camping at an area with a high sulfur content in the water. I want that stinky stuff gone as fast as possible.
US Army (Ret)
2020 Entegra Accolade 37TS
2019 Jeep Grand Cherokee Trailhawk (Toad)
FMCA - F432054