When we look at sanitizing the system it has to be looked at as a "try" to improve our odds of not getting sick. There are too many variables to actually state a specific amount of sanitizing needed! How much stuff has grown in there? Nobody knows!
So when we do add the bleach in the fresh water outlet, we do a certain amount of cleaning on that bit of tubing. The time is very short and not what we would want to call a full blown amount as it does take some time to let the chlorine work it's magic.
But it does "some" and it does help but there is also another way to look at the water inlet.
If we use water supplies that are regulated and treated as most public water is done, we will automatically get some cleaning done! The specs for public water require that there is a "chlorine residual" when the water gets all the way through the pipes and to the tap at the end. Some complain when they smell it, but it just tells me that the sytem is working as it should!
That means that you should always have some chlorine or chloramine in the water you are running through that bit of tubing! So the tube will be sanitized as you use the water, even if you do not go through a "sanitize" process!