Water Heater maintenance

[udraft]

I like to flush my residential gas water heater once a year. Plenty of instructions to be found, some variations.
The person that installed my last one (4 years ago) recommended leaving it run, open up the valve for maybe 15 minutes. Said the heat and flow would create a cycling/swirling that will rinse the sediment out real good.
Can I damage my unit doing this? It's certainly the easiest method.

 

[Silentrunning]

I have always turned off the electricity to mine when I flush them. This is in case the pump should fail or something else happen to prevent the heater from retaining enough water to keep the heating elements from burning up.