Where are you located? 3-4 weeks seems very slow for JLCPCB. Are you shipping to South America or something?If you can afford the time, effort, and expense needed to move to China, maybe you should look into working with a local board shop that could provide more rapid turnaround.The best way to improve your development time is by doing fewer iterations. Often easier said than done, but you should be designing for test and rework and thoroughly reviewing your designs before submission. You said ...