Depends on what you are cooking.
If you are increasing the number of items (say a steak, or chicken breast) and they are all about the same thickness and you bag them individually, there is no change to the time.
If the thickness of the item increases significantly as you go to a larger piece of meat, then the time can increase somewhat. But it depends on what is being cooked. Doubling the thickness of a steak will increase the cook time, but going from a 4 lb roast to a 7 lb might not because it's going to be in there for 18-36 hours already.
Changing the number of shrimp in a bag does not change the time, only changing the size of the shrimp would.
kind of get the idea where this is going?
Increasing the amount of vegetables in a bag doesn't really change the time in my experience, but I also don't cook vegetables SV much, so maybe someone else can chime in here.