New products and processes are unproven by nature, and challenges arise more often than with a change to production volume throughput (there are a separate host of issues for transitioning to moderate-to-high volume production, but they are anticipable with a higher degree of confidence).
When overseas production slows due to design obstacles or PCBs fail quality tests, response time will be critical to correct issues and navigate timelines. Geographical distance can slow the resolution of these issues, whether due to time zone differences or international flights for in-person meetings. Even for the best overseas manufacturers, a process like discussion and approval of change orders may occur over days due to mismatches between working hours. These individual delays can snowball throughout manufacturing, placing production far behind schedule.
NPIs are beset with complexity by the sheer number of phases involved. Design engineering, component engineering, compliance, sourcing, manufacturing and testing, quality control teams, and suppliers must carefully coordinate efforts to ensure compatibility between departments and compliance with the end product. One of the most significant advantages of partnering with a local CM with ample industry experience is the ability to synchronize production faster and more efficiently.