Online, because of its real-time delivery model, is, in theory, a perfect place to execute remnant inventory deals. With historically low sell-through on a site or ad and page impressions increase dramatically and unexpectedly, having a hopper filled with remnant inventory deals is a great way to ensure you're maximizing the ad revenue off of your inventory.
Online, because of its ability to deliver content instantly, is theoretically suitable for executing deals with unsold inventory. When historical sales on a site or ad are minimal and page impressions rise unexpectedly, having a reserve of leftover inventory transactions can help maximize the revenue from your advertising assets.