I would like to test Cloudflare Polish (want to try WebP for images), but my Director of UX is very concerned that this could “break” the site. I think I already know the answer, but he’s asking if we could test a limited number of pages or some type of whitelist rather than the whole site.
If this is not possible, I recommended that we could turn Polish on or off at will, but it will require the cache to be cleared. I’ve run a variety of metrics on 32 URLs and would plan to retest them with Polish turned on.
How can I run a “safe” test that wouldn’t freak him out?
Polish applies to images, not pages. So you’d have to craft Page Rules to do this.
Since you do have Polish, then you’re on at least a Pro Plan with 20 page rules. I’d try something like enabling Polish with WebP in Speed → Optimizations, then a bunch of Page Rules that turn off Polish for wildcarded image directories.
For example, WordPress uses wp-content/uploads/YEAR/… So create a Page Rule to turn Polish OFF for example.com/wp-content/uploads/202* (disables for all 2020-2021 images).