Back when I used to use Adobe Fireworks there was a shortcut for flattening the current selection, I believe it was cmd+ctrl+shift+Z and I'm pressing this hundreds of times a week and eventually it gave me RSI.
After this happened I remapped it to cmd+F, luckily the app had the ability to do that but honestly I consider it important enough that the OS should provide it. I know a lot of windows users point to AutoHotKey but it's a horrible janky feeling hack and requires you to write actual scripts.