James we really use IT (internal temperature) around here because using time temp has too many variables and we would never want anyone to become ill. IT insures that can't happen.
For instance, we do approximate cooking times, but then we have to realize the current temp and your climate, using a fireburner or and electric, low and slow or the Texas Crutch, types of wood, things that only you'd know. So instead of making a mistake and you know it would happen we go straight my IT.
I highly recommend that if you have not you sign up for Jeff's E-Course. Its a 5 day course will is great, it helps new smokers get their feet on the ground as well as the old pro's to catch a refresher. Dang ya know what I forgot to say here? Its free!
So anyway if you use trhe search you'll probably find estimates, for instance pork using foil is about 1.5 to 2 hours a pound at 230. Without foil its 2 to 2.5 at 220. but then you'll have environmental considerations, type of smoker, etc etc....
So I hope us understand why everyone here talks IT. It means that if you use the IT method no matter what else happens when the proper IT is met no one can get sick from nasty bugs. That just wouldn't be right.
Most use a remote thermometer with alarm setting, you can use a digital pen, doesn't matter what but until you have mastered your pit its the best way to smoke.
I hope you understand.