I run two job boards. Job Board A accepts unique posts as well as mirrors several client job boards. Job Board B is about to be published and has a larger scope so mirrors all of Job Board A plus accepts unique posts.
Should Job Board A use canonical tags for job postings mirrored from the client job boards? I haven't since 2008 and my search results are decent.
Should Job Board B use canonical tags for job postings mirrored from Job Board A?