Maximum time in a Mash Tun?

[Laner]

All of the threads I’ve read suggest mashing for 60 minutes at the given temp, clearly this is based around brewing in a day, but I was wondering if it was possible to leave the grain in the Mash Tun overnight if times is tight ( obviously temp would drop ).

Would this be detrimental to the outcome?

 

[MashBag]

Yes.

Hot cooling and cool warming up later (which I do all the time)