One thing to remember with "probe method" you should always, always, always use it only as a gauge.
You illustrate the example well. 175 will never been enough for a brisket. Not sure where you got 175 (I know probably the Smokin Q cookbook).
The guys have given you better temps to go with.
But even so, you need to check it whenever that temp is reached.
Take the probe and after it is reached and use it as a poke and prod method to test for doneness. I should "feel" like it's going into butter with little resistence. If it takes 20 lbs of pressure to insert it (which it would around 175 temp) then you'll know it's not done.
That's the essence of "it's done when it's done" Temp is only one gauge, but you have to use your experience as the last determinant of is it ready to come out of the smoker