• In addition to this public search, we scanned our proprietary research database of over 1 million sources and were unable to find any specific research reports that address your goals.
• There isn't any report that highlights data on consumer message/ad recall (benefits or no benefit) based on exposure to multiple 15 seconds (or other ad lengths) sequentially versus seeing them out of order.

Video Length/Duration and Factors Affecting Ad Recall

• Factors that affect Facebook's Estimated Ad Recall Lift are "targeted audience, powerful creatives, and existing awareness of your brand."
• Furthermore, "the amount of time each person spends 'looking' at an ad," affects the estimated Ad recall Lift...... "If they stopped scrolling and hovered over an ad for 9 seconds as opposed to 1 second."
• Of other factors/metrics that Facebook tracks, how much time people spend looking at ads is a key factor.
• An old report from ResearchGate shows that "the longer a person is exposed to a web page containing a banner advertisement, the more likely they are to remember that banner advertisement." Generally, there are limited scholarly/research reports in this regard.
• Based on research on how fast people stop watching different types of video ad content, published by Facebook, it demonstrates that "with video ads in News Feed, the average number of people watching the ad drops off exponentially very early on."
• The report further puts that "when it comes to measuring ad effectiveness in this new mobile era, no two seconds are equal. Earning ten seconds of watch time from millennials in Stories is harder than earning ten seconds from an older audience in a non-skippable environment."
• These suggest that companies placing ads "need to get the message out as soon as possible in the video or people will click away before they even know what the ad is about." Hence, video length needs to be kept short.
• According to the same research by Facebook, companies are advised as follows: "Within a given experience, and for a given audience, iterate quickly on duration to ensure that you're capturing attention."