I have revived this thread so I don't hijack the Waygu thread.
An interesting point is made by Mr. Byte about a Waygu brisket having little to no stall. When I asked why he thought it was, he mentioned the connective tosses, or the lack of in a Waygu versus a standard beef brisket.
This is in line with my experience as well.
It takes energy to render fat. BTUs are the energy du jour in BBQ.
If you have 1000 BTUs (for simplicity sake) and it takes 800 BTUs to render fat, you have 200 BTUs left to cook with thereby lengthening the cook time.
You use foil, you reduce the evaporation (- XXBTUs) and hasten the rendering of the fat (+ XXBTUs), thereby shortening the cook time.
More connective tissues to render = less BTUs for cooking
less evaporation = more BTUs for cooking. (foil)
Less connective tissues = more BTUs for cooking.
It is basic thermodynamics at work