Thanks, Sir Tom--have heard this innumerable times and well before the 1990s, thus suspect it dates back a long way.
The usual story runs thus: N would have a "corporal" shine his shoes will discussing orders with his generals. Once the generals departed, N would ask the corporal if the orders made sense. If not, he would revise them.
Even if there is no small amount of inherent wisdom in the basic concept, there is all manner of silliness enfolded in this particular tale, but one wonders about its provenance.
Thanks again