100%….the list of suppliers needed to build one model of bike is staggering long. That is one of the biggest challenges for factories….coordinating all their suppliers across different brands, specs, models, etc.
The SKU management makes D-Day look like a simple walk in the park. 
One of the last companies I worked for at one point had been almost 100% vertically integrated at one point….to the point of rolling the threads onto their own bolts. That obviously was not sustainable, however.