I think the way that people with longer hair use these products, and which products they choose, depends on all sorts of variables such as hair type, hair length, hair condition and regularity of washing. I will tell you how I use hair cleansing products, but other people’s routines may be very different.
I am a female in my mid-20’s with medium length (about armpit length) European hair which is naturally fine (but appears thick because I have a lot of it), relatively straight, and naturally light brown in colour. It was bleached about 2 years ago, so the ends are more porous and lack lipids, though there has not been repeated damage from multiple treatments.
When I shampoo my hair, my main aim is to remove oils from the hair closest to the scalp and the scalp surface, so I will focus on the scalp area, lather, and then pull the lather down the length of my hair to lightly shampoo the lengths. I wouldn’t expect silicones and polymers to be in a high concentration in a shampoo product as I would only expect mild conditioning and will use a conditioner product to add more conditioning to the parts of my hair that need it most.
A 2-in-1 shampoo and conditioner formulation has always left too much deposit at the roots, and not enough conditioning on the lengths of my hair, so I always use a separate conditioner product and avoid 2-in-1 products.
When I apply the conditioner, I will apply it to the lengths only (roughly below my ears) as that section of hair has been exposed to more aggressors, and too much deposition at the root will weigh down the roots and appear greasy. I will leave it for a couple of minutes before rinsing.
On the rare occasion that I swim, I will “co-wash” afterwards, which means I use conditioner at the roots and through the lengths (and skip shampoo) because the cationic surfactants will still provide some mild cleansing but the heavy conditioning helps to hide chlorine damage.
Hopefully that is of some help.