Nobody should ever use the same shampoo consecutively. Dandruff can be caused by an oily or dry scalp (both are irritating).
What everyone should do is alternate between shampoos. If you have oily hair and insist on washing your hair everyday, use the dandruff shampoo one day and use a neutral shampoo the next day (neutral meaning having a pH of approximately 5.5 - the natural pH of hair). Try to use the dandruff shampoo at most 3 times a week to begin with, and eventually decreasing the use because those products are much harsher than your regular shampoos and that itself could be irritating the scalp, thus producing more dandruff.
Once you don't see anymore dandruff, switch to using a regular shampoo but continue alternating washes with a neutral or simply different shampoo. Example: using a shampoo for volume for one wash, and a straightening shampoo the next time. What this does is that it keeps the pH of the hair and scalp balanced so that it will not be irritated, or become accustomed to the product.
Also, touching your hair constantly or massaging your head while you wash can increase the amount of oil in your hair. You hands have their natural oil, as well as your face and if you have a tendency to have oily hair, its important to keep hair away from your face and hands. Massaging the scalp will activate the sebaceous glands, thus creating more sebum or "oil."
If your problem is dryness instead of oiliness, do you use conditioner? Do you put it on your scalp as well as your hair? My husband used to wash his hair with shampoo only, never using conditioner and he always had dandruff until I pointed that out to him. He never had dandruff again.
If it is dryness you're suffering, do NOT use a dandruff shampoo more than once a week (they're very drying) and do NOT wash your hair every day. At most, wash your hair every other day but if you continue to see dandruff and it is indeed caused by dryness, I would wash it every 3 to 4 days. Some people could go an entire week without washing it. There's nothing wrong with that. Your scalp may just take longer to produce its oil which are essential for a healthy scalp, and washing more than necessary could be stripping your hair of these oils.
