Publishers run multiple ad slots (ad spaces) on each of their pages. There are several use-cases that are impossible to solve for when each auction is run independently and no knowledge of outcome can be shared with a following auction.

For example:

• A buyer may be interested in a whole page takeover where they are the only advertiser on the page, providing their own ad/creative for each ad slot on the page.
• Publishers may need to avoid channel conflict where an ad for buyer (let's say Ford) should not be shown on the same page as an ad for another (like say, Chevrolet).

Both these use cases (and perhaps others) could be solved if runAdAuction supported one or more auctions that could provide winning ads to multiple ad slots.