Without knowing exactly what you are working on, here are a few ideas:
1. Figure out if you can do fewer slow iterations. What's driving the need for a full PCBA run for each iteration? Might be able to split out to rigid assembly and flex for example.
2. Run more experiments in parallel. If you have multiple ideas or variations to test, design them all and fabricate them all. Flex antenna? Make like 30 parametric variations.
If design then becomes the bottleneck, then automate that next.
I would like to give this response a signal boost, based on the fact that the comment author knows a lot about PCB design, prototyping and manufacturing.
Gotcha - thanks for the advice. The IC performance on the flex circuit is a key part of the product so will figure out how to test that in a lofi manner.
Maybe you only need a small bit on the flex (main CPU and the DDR to prove signal integrity?), and the rest can just go on an ugly quick PCB for software validation and bringup. Stuff it with test points, current shunt points, larger parts for easy probing, add some mounting holes too fasten it to a test rig, whatever.
Then just glomp the flex down to the test PCB with some nice Samtec connectors (you can enough free samples for a small batch of test units even) or an edge connector on the stiffener.
1. Figure out if you can do fewer slow iterations. What's driving the need for a full PCBA run for each iteration? Might be able to split out to rigid assembly and flex for example.
2. Run more experiments in parallel. If you have multiple ideas or variations to test, design them all and fabricate them all. Flex antenna? Make like 30 parametric variations.
If design then becomes the bottleneck, then automate that next.