On Farming Today this morning (for those of you who aren't early wakers, it's on at 5.45 on R4 and has gems some days) there was an interview with a lettuce grower. He (well not just him on his own obviously) plants 600,000 lettuce seedlings a day on his Fenland fields. Each is spaced at the precise optimum position and for as far as you can see the rows are uniformly straight in every direction. The greenhouses are strategically placed north south for every seedling to get exactly the same amount of light to aim for exactly uniform lettuces.
I couldn't grasp the magnitude of the figure for how many lettuces he grows each year.