Gallons per acre for effective broadleaf control

I am setting up a new  ( to me) 20 ft boom sprayer for pastures and grass hay fields. When I calibrated it at 20psi, and a reasonable spraying ground speed, it was putting out 11 gallons per acre.  This is great for minimizing refills and with fan jets it should get decent coverage. But what have you learned in your experience? I will be using Grazon Next HL on pastures and Crossbow on Hay, both with surfactants. Will 11 gallons get the needed leaf coverage? I am using 20psi to minimize drift.

Gallons per acre for effective broadleaf control