Full timers who sit on full service sites, in places that have city water will not need to do as frequently.
It is the water from wells that can (note word can) cause you a bit of trouble, and water that sits in lines or in fresh water tanks for a long time cause you don't use the unit, like us long timers or vacationers or weekenders.
Al and I do ours in the spring (if we were winterized) and sometimes again during the calendar year, depending on use, etc.
We do a bit different than Icehouse, we fill our fresh water tank up, using 6 to 10 ounces at the most of clorox. Run through the pipes with the pump. Let set for 24 hours, then do the drain thing and then fresh water. BUT, we are not living in it, so have the time to let it set for 24 hours.
Have heard of suggested amounts of a LOT more clorox than we use, we can smell the chlorine with the amount we use, I cannot imagine what it smells like to use a gallon or more?? WOW!
Or how long it would take to rinse out. Whew!
Did not visit the web sites suggested here, so, maybe I am duplicating.