When it is signalled to me during my sharing that I am out of time, I stop then and there.
If the sharing time is three minutes, three minutes is not a target, a ballpark figure, or a baseline: it is a cap.
It means less is fine too.
If I get to three minutes and I haven't finished my point, that's my problem not the group's. I need to learn to pace myself better.
It's not for the last potential sharer in the meeting to pay the price of my rambling, through my catch-up time being carved out of their three minutes.
When I stopped letting myself go over time, by necessity I honed my ability to be concise.