Don, I was reading an old book called ‘Know and Grow Vegetables’ by Salter et al and they stated that field research indicated the highest yields per unit area occur at plant densities where not all plants result in edible produce.
Apparently amateur gardeners and thought leaders of the time turned their nose up at such waste, whereas farmers were supremely indifferent!
The sowing densities suggested in that book are higher than Charles suggests in several cases, although there is no detail on how yield measurements were made, whether single harvest on one date gives different results to daily pickings etc. I make no judgement, having done no trials myself, merely highlighting an interesting source of information and contentions.
I must say my direct sowings of radish this spring into soil with freshly laid compost on top have such incredible yields that modules in the main season seem unnecessary where radish is concerned….