corn pollination

[Chenango]

I just harvested my Golden Bantam corn and I need some help about pollination. Most of the ears were not full.

I had only 3 rows spaced at about 12 inches and I did hand pollination but I am thinking of seeding 4 rows next year to avoid the trouble of having to distribute the pollen myself on each silk.

Do you think I can expect full ears with 4 rows spaced at 18 inches ?

Thanks