Opening the vent on your Bradley is not something the guys on the Bradly Forum invented.
It is a known fact in the Smoking community. Does the vent have to be wide open? No sir, but it should be open enough to allow the smoke to pass by the meat you are smoking and to remove moisture the meat in your smoker is creating. Most of the people on this Forum have had success with an open vent so they just leave it wide open or maybe 3/4 open. For me I took the vent adjuster off my smoker long ago.
This is from the web site "The Grilling Spot" and it has no affiliation with Bradley Smoker
"Question - During meat smoking, when is the smoke absorbed?
Most of the smoke is absorbed in the first hours of smoking as most of the juices are later lost and the meat 'caramelizes'. Less smoke is absorbed during the latter part of smoking.
Some meat smokers have a chimney to convey excess smoke out while others simply have vents or dampers or a combination of both. The main focus in smoker cooking is for the smoke to encompass the food as it cooks, the food gets a 'smoke bath'. Not too much, just enough to flavor your meat. Allow the air in the smoker to circulate, crack open the vents for smoke to escape. Do not allow the smoke to stagnate. Maintain a 'smoke-flow'."
That should be a "No Brainer" Vent open equals Good, Clean Smoked Meat.
Now length of time to smoke something is entirely up to the person smoking the meat and the people eating the smoked meat. I personally like smoke. Butts, I smoke 6 hours plus, Briskets will get 5 hours plus and my plus is usually 2 to 3 more hours. I also know that meat stops asborbing smoke somewhere in the 140 internal temp at a 1/4 deep into the meat. So all the extra smoke after that is just feeding the bark.
Last thing I will say is, You bought and paid for your Bradley and you are entitled to cook with it any way you want to. If you screw it up by smoking with closed vents, then you have nobody to blame but yourself. And if you are trying to preach a new way of smoking with the Bradley, I don't think you will get any followers.
My $0.02. Good Luck to Ya!