I haven't really experienced this, also having worked at both small and large companies. At the small companies, most of the prototypes failed (which is the whole reason you're prototyping) and then the ones that succeeded usually got rewritten because everything got rewritten multiple times. At the large ones, the prototype exists to convince a VP that this avenue is worth pursuing, and then typically it's handed off to another team to actually do.

Could also be because I've basically always had technical management, and the projects I work on tend to be fairly technical in nature (i.e. "can we do this?", not "the customer wants this by Monday").