You also have to take in consideration do you completely stop production of an existing type to make the modifications need to your current production lines? and then upgrade your whole fleet which could put them all out of action for several months at least
in war time this often inst a very practical solution.
More of the stock standard and less of the wizzy toys is often whats needed in war time... Germany kinda found that one out the hard way. And if I recall correctly Germany war industry wasn't even working around the clock 24 hours a day till early 43 when they had been at war since 1939!
The Uboats failure imho was simply not enough boats at sea in 1939 to achieve the desired effect.