Apple's Photos People and Pets: "Review More Photos" doesn't work.

You may want to try it the other way round. When you are seeing an unnamed face in a photo, click the thumbnail of the face below the photo to open the album. Photos may have started a second album for this person and you have to merge it with the main albums for the person. When Photos opens a separate album for this person, with only a few faces, name this person to merge it with the main album, then try again "Confirm additional faces".

That is why I am no longer trying for long system up-times, but are restarting the Mac and then Photos occasionally. This will ensure that all background processes keep running or are restarted, if need be.

When Photos is taking a very, very long time to analyze the library or similar, I am keeping the Console open to see, if there are frequent crash logs or spin reports for Photos. If there are frequent crashes, I am restarting in Safe mode, to clear caches and check for older apps, that might be using unsafe frameworks and need updating.

Also there may be "bad apples" in the Photos Library, videos or image files using a legacy codec, that Photos can no longer process, or items with missing originals. Such items can cause the photos analysisd to try over and over again to analyze them and get stuck. I have tested all videos by exporting the original files and reimporting them into another library. The videos giving an error message on import I converted to a different format.