Switching vendors mid-project usually costs thirty to fifty percent of what you already spent, plus two to four weeks of delay. That is not the new vendor quote. That is the hidden reset tax.
The new person must reverse-engineer decisions that were never documented. Why is that button there? Why that spacing? Why Next.js over WordPress? Without answers, they rebuild or guess.
Design files without a matching codebase are half an asset. A Figma file from a designer who did not build creates a second handoff gap with your next developer.
Code without design context has the same problem. A developer who inherits components without understanding user flows will refactor what should have been left alone.
Client morale drops twice: once during the painful transition, again when the new vendor re-estimates everything you thought was done.
Zero Handoff reduces this risk because one person holds design and code. If you must switch, switch at a milestone with full export: Figma, repo access, decision log, and analytics baseline.
The cheapest project is often the one that finishes with the same person who started it.