I’m sorry but silicones do not build up on hair. This is all part of the myths and legends of the marketing department of the shampoo manufacturers
Silicones are washed off completely when you shampoo your hair, particularly if you use a decent surfactant such as SLS, but even a secondary surfactant will do so as well. There is absolutely no need for a ‘clarifying shampoo’ which is just plain shampoo. Which you can see if you read the ingredients list
In theory, this is all true. Silicones in conditioners are designed to be washed off the hair and they are pretty easy to remove. In practise, most people don't wash their hair properly and most shampoos are not designed to remove everything from the hair. They'll do something secondary to cleaning, which means leaving something behind. For example, my shampoo has argon oil and keratin in it. There's no point putting that in if it's gonna be washed out at the same time. It leaves a residue on the hair. It's what it's designed to do. There are no targeted cleansing ingredients that remove everything except argon oil and keratin, so to work it has to not remove all of everything, including silicones.
A clarifying shampoos only job is to cleanse the hair. It doesn't leave anything else behind and generally has a higher level of cleansing ingredients.
I use mine when my hair starts feeling 'heavy' straight after a wash.
Proteins, oils, silicones and anything else your shampoo or conditioner claims to 'infuse' or 'nourish' your hair with, will (mostly) wash out the next time you shampoo. You cannot permanently repair damaged hair. Anything that tells you you can, is lying. You can disguise damage and prevent it travelling up the hair shaft by coating your hair in X, Y or Z but the only way to truly fix it is cutting the damage off.
If your hair needs protein, it depends why it needs it as to whether you eat it or coat your hair in it. Hair that is growing weak, doesn't have enough protein when it is forming, so you need to eat more protein. Hair that is chemically or heat damaged needs to be coated with protein. For severe chemical damage i.e your hair is mushy and hard to comb when wet, there are treatments that seal protein onto the hair shaft with heat (aphogee two step is what we use) but even they wash out over time.
If you do have chemical or heat damage and you can afford it, it's worth finding a local salon that offers Olaplex treatments. Olaplex is the only product to date that can actually repair the hair but it can get quite pricey. Even then, it's a hair product, not a magic wand. If you've bleached the absolute crap outta your hair, Olaplex will reverse some of the damage but it's not gonna take your hair back to it's virgin condition.