Do they work in what sense? What are you wanting them to do? If your hair is badly damaged, for instance, no, a salon treatment won't repair it. You'd need a trim first. And then you'd need to change the way you've been treating your hair overall. It just depends on your expectations.
Personally, I'd rather spend the money on my own deep conditioner (Curl junkie makes two really good ones) and apply it to my own hair whenever I want. This is because it would be cheaper, more convenient and better for me since I'm on a modified CG rooutine and am picky about my products.
But no, the treatment won't hurt (unless the product's ingredients are inconsistent w/ what you need).
3b (with 3c tendencies) on modified CG