No pun intended - you could make the case of police not waiting for others to arrive! This is not the first movie to have the main character being way too anxious (not always with apparent reasons - the first incident ... it makes sense she wants to go in, not wanting to wait ... second one? Well I reckon in the end it makes sense, but she can't know that - also .. "baggage").
All that aside, the movie has quite a few things it does bring across. Having the chance to do things over, is not always the best thing for humans. It may feel like a security blanket ... but we know how this works. There are things, that I am not sure how they ... actually make sense and happen (I reckon technology is involved), but in the end, how much do we remember? How much is true? If we don't remember, did it happen? And are we a different being all of a sudden? A lot of existential question and .. angst as you could say ...