That's cool. One would think mine's cleaner, but it's got its own problems involving it not recognizing a new image as different if the filename is unchanged,

That's cool. One would think mine's cleaner, but it's got its own problems involving it not recognizing a new image as different if the filename is unchanged, and even if I do staggered updates the only way to reliably make sure it takes every single time is to quit the Finder, which I of course refuse to do. It will, at times, decide it doesn't want to take for hours on end, with an image that updates every ~10-15 minutes, and then will later decide to start updating again, with no other state change having apparently happened to instigate it (e.g., rebooting, logging the session out, etc.). It may just be my experience, but over time macOS is behaving more and more irregularly in more and more ways, for completely inscrutable reasons.