There are 4 basic types of sweet corn:
Super sweet
Sugary enhanced
Synergistic
Old fashioned
The first three tend to be problematic, because germination can be spotty. Planting treated seed helps. Planting into well warmed soil helps.
I don't like super sweets and synergistic corns, because they taste medicinal to me. I really like sugary enhanced, but don't grow it, because I won't intentionally poison my food, and it doesn't germinate reliably for me without poisons.
So I grow only old fashioned sweet corn. It's reliable, chewy, and not too sweet.
I allow about 2 to 2.5 square feet per plant. Planting several short rows in a block works better than one long row.