Patrick,
If you are talking about precooked brats like Johnsinville then you only have to leave them in for two to three hours. They are already cooked, so the only thing you need to do is warm them up and get some smoke into them. I did some yesterday, along with some artichole and garlic sausages I got at Costco, while smoking a couple of eye round roasts. The sausages only took about two and a half hours before I took them out. The only thing you want to make sure to do is pierce the skin on each sausage with the tip of a knife a few times. I read about doing this to keep the sausage from splitting, or even blowing up, while in the smoker. I know that when I grill them they split all the time, but I don;t care then because I am just slapping them on a hotdog bun with mustard. Mine that I smoked yesterday didn't split at all.
I am new to this smoking stuff because even though I have been grilling and barbecueing for decades I just got my first smoker a week efore Father's Day. It was an early Father's Day present from my wife. She said it was a gift that would keep giving back to her in the form of good que. I have been reading a lot on the net and have learned a lot from it.
John
