On average, 10gpa. But now with the larger sprayers, if I can, I go to 13 gpa where possible.

 On this farm, I did some comparing a while back and found that I had better coverage at slower ground speeds. Slower speeds had less residue shadows and better canopy penetration for my sprayer setup.

 I also sprayed a field with glyphosate using the tee jet Y that used 2 nozzles on each nozzle body. Not a single nozzle with 2 outlets, but 2 full on nozzles. I used 2 turbo tee jet induction tips and 20gpa. I had never had such great control with glyphosate before that. The main issue with that setup is I cant rotate the bodies to a different tip when needed as the bulk of the Y with 2 nozzles would hit the booms. 

 IMO.