If you wait to assess corn stands and spacing at harvest, you will just be guessing why there is a long gap in the field. Doubles are doubles and easy to spot. But if there is a gap of 12 to 20 inches, maybe more, it's hard to tell if that's the planter's fault. Perhaps the plant germinated, emerged and was damaged by insects or diseases. Perhaps a bird ate the seed out of the row. Or perhaps the seed simply didn't germinate.
One farmer who scouted his fields of young corn recently let us tag along. He found a few plants affected by black cutworm feeding, and a few tiny holes from some other insect, but not enough of anything to warrant treating the field with an insecticide. However, by walking and digging, he did get a handle on whether the stand issues he found were related to the planter or to the seed itself.
In one location he dug up a seed that had never started to germinate. It was at the proper depth, and plants on both sides of it germinated. Sometimes that just happens, the farmer noted. That's why germination on the bag is usually 95%, not 100%. Not every seed will germinate.
If he had waited until fall or even later in the season and found the missing plant there, he could have assumed it was a planter malfunction and just a skip. Maybe the seed didn't drop even though it was supposed to drop. By finding the seed he knows the planter had nothing to do with it.
Scouting early helps him get a better handle on making decisions for next year, because he has a better idea of what actually happened this year, the farmer notes.