I agree completely with Pete’s comments regarding building a trusting relationship with your PCB fabricators.
He also brings up another good point regarding cost, to which I pose some further questions:
How much time and effort (resource) are dedicated, during the PCB design process, to preparing the board for fabrication and manufacturing?
For instance is more effort dedicated to ensuring that the electrical constraints/performance of the board is met?
Are the electrical constraints met first then fabrication and manufacturing requirements addressed later?
How much are you prepared to compromise yield to ensure that electrical constraints/performance are met?
Food for thought?