How many is too many?

I always sow more than I think I need for tomatoes or anything else that needs an early start and I feel I won't have time to try again. The amount of over-sowing is gauged by source. Trusted seed companies and seed swap seeds just a couple extra, less trusted sources several more.

For big guys like pumpkins and courgette, I sow what I want and try again in a week or so if they don't come through. I never seem to sow enough peas or beans.

For tiny seeds, I just sprinkle and hope for the best.

I have neighbors on my street who will pick up any plants put out on the garden wall and friends at the allotment who will take anything else. Only my poor stewardship tends to cause the end of any spares not any intentional thinning or composting.