Not in the least. I am assuming you mean a few times a week and not everyday right? If you get a really good cosmetic shampoo that makes your hair look nice and thick and healthy, after awhile it will stop having that cosmetic effect. Your hair gets used to shampoo it seems. Thats not probably not the best way to put it, but oh well. Personally I have 6. I will use about 4 a week.
I have and rotate
Nizoral
T/SAL
TIGI: Thickening shampoo
TIGI: Control Freak shampoo/conditioner
TIGI: Manipulater shampoo/conditioner
TIGI: Bed Head moisture maniac conditioner
TIGI is a very expensive store bought product, but if you go to a Salon when they have a sale you can buy Liter bottles for $10, which basically makes it cheaper than any of that crap all of us used to buy at a grocery store when we didn't care so much about hair.
I've said this before, but you guys should really look into Xenna 183 shampoo. It is a coal tar based shampoo, which the company recommends using everyday, that also contains a patented ingredient called "L-toc", which thickens the hair. They also had some interesting studies,I believe using liquid chromotography, in which they showed the ability of the shampoo to inhibit DHT within the scalp (take it for what it is worth). Great shampoo for fighting inflammation and at thickening. I highly recommend it! It will put the t-gel shampoo, etc to shame!! http://www.xenna.com.