Even spacing is important because the corn seedling produces a chemical (i.e., an iatrogenic chemical) that inhibits the growth of other corn seedlings. The magic number is 6 inches. For 30 inch rows, that is a perfect population of 34,848 seeds per acre. It is easy to lay out a tape measure but a mind numbing exercise to collect & analyze the data. If you do, the results will blow you away. Without this data, please don’t tell me how evenly your planter drops seeds. As planting population goes up, planting accuracy needs to go up exponentially, or you had better deal with the issue (narrower rows, double rows > 6” apart, genetic lines that are not affected, equal-distance planting, etc.). This effect is separate from even seedling emergence, soil compaction from planter/tractor compaction, etc.