T.S.
I can see your point although I have never tried it.
If you want an instant fleet (well, as instant as is possible), unmothballing and retrofitting will get you a fleet faster than any other method.
All you need is a lot of ships with repair facilities hanging about and the resources to absorb the additional 50% cost (30% to gut the old component plus 20% to install the new components) as well as the cost of the components themselves.
Very expensive as you say.
But then it may be cheaper than having a smaller fleet hanging around doing nothing.
