I'm regularly switching between my MBP's internal screen and an external 4K display (in clamshell mode).
When switching back to the external display, many window sizes default to something that fits the smaller internal display (Finder, Safari...).
I have set up a snap area on the external display to quickly resize a window to a more convenient size when it's dragged on.
By design, a window restores it's previous size when it's dragged away from the snap area (unless the opt key is pressed).
So I always end up dragging windows on the snap area, holding opt and then dragging them away a bit, so the new window size "sticks" and I can later move the window to a different part of the screen without causing a resize.
It would be great if there was a way to make a window that's dragged to a snap area forget it's old window size - either as a property of the snap area itself (I think I'd actually prefer that) or as a function that can be assigned to a shortcut (I can see "Restore Old Window Size" already exists, but not "Forget....").