I have a z-spray max, it's awesome. Anyhow I have the lavender nozzles, run at 40psi, at 5mph, and have a foamer for larger areas (athletic fields and large yards) Obviously,depending on terrain maybe a little faster or slower. I am wondering within what percent error can you get (within 10% 15%..etc?) ? I understand on big areas that are not perfect squares there is more overlap. I have calibrated a few times and talked to the guys at LT Rich numerous times. Just wondering how accurate you guys are getting? I seem to be putting a little more down on the larger areas and right on for the smaller yards.