Hahahaha no need to overthink it too much.
You have the main part down that it's ready when it probes tender ALL OVER.
The IT will tell you when to check for tenderness. Just be sure to put the probe into the thickest yet center most part of the FLAT muscle, not the point. Also understand that getting an accurate probe placement in this magical spot is actually a difficult thing so I use 3 probes aiming for the spot from different angles and go with the lowest one. I check for tenderness when the lowest reads 200F.
So again its done when it's tender ALL OVER.
As was mentioned earlier in this thread, there are many different opinions and approaches that people take.
I go fat side up, unwrapped the whole time never opening the smoker until time to check for tenderness, with smoker temp at 275F and make AMAZING briskets. I also run 100% Mesquite smoke from pellets in my
AMNPS which is part of the magic.
So when I say "don't overthink it too much" that's because my approach is drastically different then ones you are seeing but everyone here is making brisket they love!
The key is to stick to the true fundamentals of smoking a brisket and u will be ok.
Now some other fundamental things not mentioned.
Timing the smoke/cook... maybe the number 1 reason people fail briskets. Brisket is a cut doesn't care what temp it is cooked at. At 275F smoker temp, unwrapped, and not opening the door until thermometer tells me 200F IT so I can check for tenderness... my briskets take just over an hour a pound.
IMPORTANT: Pick temp you will smoke at and research how long the brisket may take on average and then add 4 hours to that time. Take that total time and start that many hours before you plan to serve and eat.
If the brisket takes longer, no problem. You have 4 spare hours for it to finish.
If the brisket finishes 4 hours early, then awesome! Tightly double wrap in foil. Tightly wrap again in 3 bath towels and set on the counter until time to slice, serve, and eat.
Example: A 15 pound brisket takes me about 16 hours at a smoker temp of 275F so I start the smoke 20 hours before I want to eat (this means an overnight smoke... all briskets are unless super hot and fast or put in the fridge and eat the next day).
So learn how fast your smoke may take at your temp and if/when you wrap.
Wrapping...
If you wrap too early you will end up with brisket that tastes like oven roast beef and that defeats the point of smoking the thing to begin with. If in doubt wrap when it's IT get's higher or don't wrap at all. I've found that if waiting until IT of 170F or so you will never end up with roast beef flavor. Hell I go to 180F on anything I'm going to wrap and have found it works for beef and pork and is basically a "one size fits all" approach to avoid the dreaded oven roast flavor.
Tenderness... you understand this. Most people starting brisket smokes don't understand this AND they don't figure out their timing and they pull their brisket early and have a disappointing failure.
Trimming... you have some things to try. No one ever gets trimming nailed the 1st time around so I'll let this be a learning lesson for you as you have some things to try already hahaha :)
Finally...
Understand these important fundamental areas of brisket cooking, you will come out with good results that you then improve upon with each brisket smoke :)
I hope this info helps :)
