I'm no expert,but I'll give a couple thoughts,until the real experts get here.
Well,I could give at least a dozen things that could affect the timing of a "butt/shoulder" and about the same for "a brisket".
Reference the internal temps,Smokin' will give you the standard,but most important answer "it is done when it is done".
Smokin' gets a royalty of $0.05 every time we use that comment,which is why he is a rich man.
![Big Grin](/static/images/graemlins/icon_biggrin.gif)
I guess if I'd give you a start point,assuming you have a correctly calibrated therm,placed in a good place,You could start checking the butt for tender around 193º.If I was going to slice it,maybe around 185º.
I'd guess most cooks might say to do the same with a brisket about 195º.If I was doing pulled,or chopped brisket,maybe 200º.
Remember these are places you will start poking it with your temp probe,or a two pronged meat fork.
Hope this helps a little.