you need sterilize entire system periodically. and completely empty/refill tank once in a while

I totally believe that the system you have requires this, but plenty of others do not.

Here's the maintenance manual for the one I have. The sterilization and emptying/refilling are done as part of the filter replacement, and not otherwise:

https://www.whirlpoolwatersolutions.com/wp-content/manuals/W...

" Maintenance consists of changing filters every year or two." it's not same as "disconnecting lines and pouring bleach inside when i change filter" or using "Manufacturer recommends using the Model 7301203 Sanitizing Kit"

You need to change filters as recommended, change o-rings, and bleach the fittings. Algae will develop on those. Thats pretty much it.

I wouldnt run bleach through the filters. The filter medium saturates, and any further use will just recontaminate water