Have you ever heard of this tradition?

I started watching Silent Witness and they have to exhume a body. They begin under cover of darkness but one of the people in charge insists the coffin isn’t moved until dawn. Is that a superstition here? I wouldn’t be surprised if this is a thing I haven’t heard of because I have, unsurprisingly, exhumed zero bodies in my life. But when I google it I can’t really find anything to explain why this would be a tradition / superstition. Looks like it takes a big team to exhume a body so surely they don’t want everyone waiting around on overtime pay in the cold. Just start the exhumation later? I realise it is a fictional television show but this seems quite silly.