Twice a day is not needed at all, I have tested it out and once a day is plenty as long as the CS your using is over 50ppm.

And when using the spray it's important to know what it's doing... it's not stressing the plant out to turn it male, what it is doing.... is the silver particles are so fine that when the plant is sprayed they actually travel into the cells of the plant itself and the silver is binding with the ethylene hormone in the plant which tells it that it is a female. The rosin is safe though and it can be pressed off the bud, silver free.