What am talking about is this. Say you just applied a levels command to a layer. With this function (and a convenient shortcut) you could simply select the next layer and repeat the last used function with the exact same parameters.
A number of functions have their own "Play it again, Sam" function already (Ctrl+F for last used filter, Shift+Ctrl+T for the last transform, etc...). But there is no grand-daddy of them all - a one-stop-shop for the last function used so it could be repeated on multiple objects
The engine that tracks the last function is already there, running the Fade command. It seems to me the road is already paved for adding the function that could be very useful when doing repetitive tasks rather than having to create an action each and every time.
I even suggest a shortcut: Shift+Alt+Ctrl+F (as opposed to fade which is Shift+Ctrl+F). Photoshop erroneously claims it's being used for "New Document with last used settings", which has been deprecated since Photoshop started tracking that by default in the File/New dialog box. Unless there is an image in the clipboard that is, which can be purged by going to Edit/Purge/Clipboard.
I have been expecting this as a logical upgrade for years now, and I'm really surprised to see no one asked for this in here. Although I heard a source say it has been brought up to the Adobe team in the past.