In the Photos app, there’s a useful button that I don’t think a lot of folks know about:
The icon that I’ve indicated in yellow above toggles what’s called Split View on and off, and it’ll only appear when you’ve double-clicked a single image to open it. What it does is pretty handy—it’ll let you see all of the other pictures within that same moment in a sidebar next to your current photo.
This is really useful if you’re making edits to a bunch of similar images all at once, especially if you want to copy and paste the same adjustments from picture to picture.
And there’s one more setting that can help you use this feature. It’s under the “View” menu, and it’s labeled “Display Square Thumbnails in Split View.”
(Note that the option will be inaccessible unless you’ve double-clicked on a single image to open it as above.)
With that on, Split View will rather unsurprisingly show the thumbnails for your images as squares, no matter what the pictures look like.
With that off, though, you can get an idea of how each image actually looks—whether it was taken in portrait orientation or landscape, for example.
It’s less neat-looking, but it’s more informative, certainly.
In any case, this Split View feature will help you check out your moments and edit them appropriately without having to swap back and forth between your library and the picture you’re currently editing. And all from that tiny little unassuming toolbar button!