How did the brisket feel when you took the temp? Did it feel done? Many here use temp as a gauge to see when to check for doneness and the use the feel of the brisket to know if it is done.
I believe that you are right in your assessment. The connective tissue will still need the same amount of time to break down at that temp. If you had increased the temp, then the connective tissue would have broke down faster. Do a search for high temp brisket for more info.
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