This tutorial features the Feast Plugin, which contains enhances and extends your theme.
Updating the content width to 728px allows for "leaderboard" ads to be displayed, potentially generating more revenue for publishers running ads.
In the past, this would have to be implemented via a theme update or new theme release, which would require everyone to reinstall and reconfigure their theme.
With the Feast Plugin, we're able to offer this as a simple checkbox to anyone that wants to enable it.
If you're not running ads, ignore this.
Anecdotally, we've heard that this can increase overall RPMs 1-3%.
For someone earning about $4,000 per month, this can mean close to $1,000 per year in additional earnings
At $8,000 per month, this can mean almost $2000 per year in additional revenue.
Cumulative layout shift is a potential issue, because leaderboard ads are 728px wide by 90px high. The most common type of in-content ad is 300px wide by 250px high.
This means that ad slots may be re-sized to 250px height, 90px height, or collapsed entirely if no ads are returned.
This remains an issue for ad networks to resolve.
There are no known accessibility concerns with this change.
The desktop size for the modern thumbnails in the Feast plugin are set to 720px, and will remain this way.
This is due to ease of configuration (providing a single image size for all themes, and theme widths) as well as avoiding the unnecessary regeneration of thumbnails when someone switches from 720px to 728px.
728 - 720 = 8px = 4px per side = not noticeable
This is especially true given that desktop typically only makes up about 15% of pageviews.
This change only affects desktop, and has no impact on mobile devices.