A seed must be planted at a depth where it can successfully take root, but not so deep that it will exhaust the energy of its endosperm before starting to gain energy through photosynthesis.
Generally I take the advice of the farmers almanac or the seed pack when planting. I am an experimental scientist but I have little interest in conducting an experiment on proper seed planting depth. I just want good produce and follow the advice of those who have done it before and hopefully received good results.
What factors do YOU see influencing how deep to plant a seed?
If you win , nothing. I get the prize in the form of learning something new.
If you lose, however, you win the prize.