if all you run is hydroton... then you can water much more often. but with rockwool, you want it to saturate, then, slowly dry .... then before it's too dry, it will water again.My current grow cannot handle the 15min every 3hour watering schedule that most recommend. I removed one watering in my 12 hour cycle. Yes you can clearly over water with hydro.
there are many many ways to skin a cat. If you watch closely for signs of overwatering, and taper off accordingly, then you will be just fine. Watering schedules are completely dependent upon media and grow room conditions.