and that's the part I can agree on, the rest, hmmmm.
Your whole idea about cleaning filter components is more or less correct, EXCEPT that it ALL depends on the stocking levels/bio-load the filter is supporting. If it is at it's upper limit, then, yes, rinsing the media in tap water can have a dramatic impact on the systems balance. Given that the vast majority of filters I have seen available are rather weak for the applications they are rated for, I can very easily see havoc being wreaked by rinsing the sponge media in tap water.
Also you need to understand that some things happen pretty much instantaneously, such as chlorine killing bacteria on contact,
(why do you think they use it?) The problem with it is that for the most part no two cities water supplies are going to be the same, and as chlorine readily dissipates, and it is routinely added/supplemented, you can never know with certainty what the levels are from day to day.
The answer is redundant systems, but most folks don't want the added expense/work of maintaining two filters and ideally two different types of filters.
as to the OP's initial question. If you have a heavy stocking and/or feed heavily, than you should be cleaning/rinsing out the sponge/mechanical media weekly or bi-weekly at the least. If it has been months, then you need to clean the entire lot as I'm sure there is muck clogging the bio-media by now and then adopt a weekly routine of cleaning and water changes.