I did a science project on this once actually. I am going to say yes and no. Hair is natural and grows at different rates for different people depending on your diet and genes. Lots of peanut butter makes hair and nails grow really fast. I eat peanut butter by the jar and I can't keep my nails cut. ON average, hair grows about 6 inches per year, or 1/2 inch per month. This is aveage. It wil probably grow faster with a diet high in food like peanut butter, and if you have good hair genes. Shampoo that claims to make your hair grow faster is true because it prevents breakage. If your hair isn;t breaking then yes it is going to grow long. But they can't really make your hair grow FASTER because they can't alter your genes. Although they can infuse your hair with the vitamins it needs (like that in peanut butter). So as for helpgin your hair, YES because it prevents breakage and promotes healthier hair all around. But as for growing faster (which I now just realize isn't what you asked) I'm going t say in most cases not that much. Hope I helped.
I can recommend 2 out of the ordinary products that would grow your hair faster.
1. Miconazole Nitrate: It's an ingredient found in Monistat (yes, I know, the yeast infection cream) and Neosporin AF. With proper googling, you'll find that both have been proven to grow your hair up to an inch per month. I tend to buy Monistat online since I don't feel comfortable buying it in the store.
2. Mega Tek Cell Rebuilder: Though very expensive ($21-$30), it is a horse shampoo that works on horses AND Humans.
Try the longhaircareforum.com to read up on some positive reviews.