Late to reply here......
the shorts, maybe as little as 3 hours @ medium heat.....go to brisket / butt-like probe tender.....
Beef backs, 4~5 hours low medium to medium, maybe use a toothpick test where it slides in real easy & you get clear juice......watch for a lot of bone pullback on these too....
Pork backs, 3-1/2 or thereabouts....usually benefit from a wrap on those....
Spares, if full size, 5+ hours, I usually don't wrap on those, but you could if you want to flavor up in some way.....
Hope we didn't miss the boat by getting to wrapped up on burgers & not seeing the question !!!!