Cost Efficiency vs Capacity Efficiency

Standard commercial lorries show why cost efficiency can work when an acceptable replacement is easy to obtain.

Fighters, destroyers, and aircraft carriers cannot simply be hired to cover a shortfall, and even hired equipment would need suitably trained crews.

For the crew and cost of one large submarine, three ordinary boats offered the Royal Navy more units that were each nearly as effective in its judgment.

Cost efficiency works much of the time, while capability efficiency remains necessary alongside it.