Benefit of linking a campaign to zones
The main benefit of linking an entire campaign to one or more zones, is that all banners in that campaign will be linked to all the selected zones. The Revive Adserver software will use the dimensions (width and height) of the banners and the dimensions of the zones to automatically match everything so it fits. A 728×90 pixel leaderboard size banner will only be delivered on 728×90 leaderboard size zones, for example. So this will save you considerable time.
This applies even to banners that you add to the campaign later, after linking the campaign to the zone(s).
Keep in mind that if you create an additional zone in the future, the campaign must be linked to that new zone as well.