Resting, wrapping, this temp, that temp all work to get it tender but only testing it will tell you when its tender. I use a tooth pick instead of the probe as I think it gives a better feel of what's inside then the probe also smaller hole in the wrapping. It should feel like your pushing it into room temp butter nothing in the way of chatter or force while it gets pushed in.
This is my process but I'm in Nevada and very low humidity ( don't know if it matters but my cooks don't seem to take as long as most peoples)
225 degrees ( set by probe on rack not by the controller) till 155 to 165 depends on the time of night and how much sleep I want
wrap in foil ( fastest cook ) paper ( adds an hour or 2 ) don't wrap ( adds a couple more hours ) I do add a 1/2 cup of beef stock at this time
back in smoker at 275 degrees till 195 to 205 and then check every half hour with the tooth pick. My last brisket took 9 hours and weighed 14.5 lbs rest about 4 hours and was great
I trim but not close and cook fat down on the horizontal smoker and fat up in the vertical smoker, I do turn them around about half way through the cook just to manage hot spots in the smokers.