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)

 

[marshbrewer]

Yes it is, if you search overnight mash on here there are several discussions around it, so it's an actual thing if you see what I mean. As long as the temperature doesn't drop so low that you risk lactic acid bacteria turning the mash sour you should be fine.

In my experience, long mashes create a wort that is highly fermentable so your attenuation can increase, but I've never found that a problem specifically.