Rick, when I'm working with bigger, easier seeds, I do space them and plant out individually. But with tiny seeds, like say, digitalis, I just sprinkle them in the milk jug. For plant out, I cut them into squares with a knife, and plant hunks. A few might be lost along the way, but when I have so many, so what?
I always plant tomatoes individually.
Lobelia cardinalis wintersows well. To plant out, I dig one big hole in a mostly shady out of the way spot, and transplant the whole jug full of soil intact. That first year, it just grows a nice basal rosette. In fall, I transplant the whole thing, intact again, to it's permanent spot in the yard.
I have little experience in vegetable growing. But I can tell you that root vegetables like carrots and beets need to be spaced enough that the root has space to expand and form the vegetables. And one beet seed can actually contain several beet seeds.
Karen