Copying save slots: useful or superfluous?

I'm curious. In games that feature multiple save slots to load from and save progress to, how valuable do you find copying data from one save slot to another?

To be clear, I'm not asking how to copy save slots, rather if this is a feature one ought to include in games. I realize it's not a necessary feature, but do you tend to think it's one worth the time and effort?

I'd imagine it's contingent on whether the game has automatic or manual saving. With manual saving, you can easily overwrite files or save progress to empty files if you want a copy at a particular moment. With autosaving, copying would allow you to suspend one file at a particular point.

Part of why I ask is because this feature seems be in not nearly as many games these days.

Depends on the game and how much can go wrong or right. If you can always get out of a tough situation (say, restart a stage if your save point is just terrible) then I prefer the immersive approach of just playing ahead and not "cheating" by splitting saves, etc.

If there's a reason to split your progress (like a turning point for multiple endings in the middle of the game) then this would be welcome for sure.

well, copying save data is something I like to do, but if your game lets you save in any slot, it is not needed as a feature I think.