Why can't you just plant seeds the recommended length apart instead of planting them and then having to thin the seedlings out?
You can plant them the recommended length apart. They will be fine. I had an entire garden doing that. There are still times when you must thin anyway, if they are on the same mound, and one or two of them are dying it's better to thin the dying ones so that they aren't taking moisture from the one(s) that is living. If they aren't on the same mound you have nothing to worry about. Hope this helps!