Technically, if you reach a point and simply save without ending your turn, when you load the game, the timer won't increase by +10:00 (the so-called "memory time"), but will remain at the value at which you saved, and then you can use replays, etc., without it being obvious.
Added 1 minute ago
At least because it gives the opportunity, for example, to check an object after recording.
Added 1 minute ago
And why is it even needed if there's autosaving? To gain something for yourself?