Different soil different plans. We have enough clay in our soils that leaching isn't much of a problem. I put on between 140 and 190 pounds N depending on yield goal for that zone with 60 to 70 percent up front. We put the second application on around V6 or V8 so about time of rapid uptake on N by the plant. Probably half of the acres around me are one pass and done. My theory is if the corn has burnt up at the time to side dress I've got probably enough left in the tank to give me whatever the potential is. If it looks good the last 50 pounds or so will be enough to produce all we are capable of.