Maximum cooking time for beef joint in slow cooker? I usually cook a joints of beef by browing it in a pan and then putting it in the slow cooker all day (about 8 hours) completely submerged in stock.  

At the weekend I have family coming over, so the joint I have got is twice the size of the usual, and we are eating a couple of hours earlier than usual. 

As I do not really fancy getting up in the early hours of the morning to put the beef on, I am thinking about putting it on last thing at night. This would be a cooking time of around 15 hours. 

Is that too much? Is there a maximum time that beef joints (or any meat, for that matter) can be cooked in the slow cooker? 

Would I be better to cook it the day before and then reheat it?
I do think there is a maximum to the duration of stewing a cut of beef. There is in my opinion such a thing as too tender and soft. If you plan to cook the meat as one large chunk you will have to add a little to your normal stewing time, but I would not go as high as 15 hours.

Cooking and re-heating is quite an interesting option though, as quite a few dishes benefit from this in terms of flavour. Perhaps a general question on this subject, or a more directly relevant one would be of interest to you.

For me, the smaller the size of your chunks of meat, the more you should stick to your normal stewing time of 8 hours and the more you could consider making it a day early to enhance the taste.