If i want to make 30 sandwiches at once, how does it change the time in the oven ?

Hi, thanks so much! It really depends on what size Dutch oven you have. If you can comfortably fit 7 1/2 pounds pork shoulder in one pot, then go for it! It will take longer to get tender, but just follow the same cue as the original recipe: It's ready when you can easily shred the meat with two forks. And if you don't have a big-enough pot, I'd just divide the meat into two pots and cook those at the same time (assuming they'd fit in the oven at the same time). Hope this helps!