gingal,
I am using Keratase, Bain Gommage for my oily scalp. My hair therapist advise beginning to use alternate days... but if any point of time, u feel tightness in ur scalp, change to twice a day... and slowly change to once a week. Try that first, it is does not work for u, u gotto get treatment ampoule for the scalp. I used once cos i dropped too much hair.. It is a one time thingy.. (abt 3 months) after that, back to treatment shampoo only.
Also, please dont use rejoice type of shampoo, for oily scalp it is not advisable to use 2-in-1. Best to use just shampoo and conditioner separate. For shampoo, get those for daily use to alternate with treatment shampoo.