I believe a lot of my issues used to be from tamping. I wouldn't tamp often enough, and when I did, it was too hard. Still when my pipe is going nicely, I forget to tamp when I'm lost in my thoughts. Trying to remember it more frequently.
Burgers are most of my diet, for the past 20 years. I usually eat one weekly, sometimes 5 or 6 a week. Bacon cheddar pickles and ketchup is what I get when I'm out. At home I also like Frank's red hot sauce on em.
If I had to give a real answer, I'd say about a month before it starts drying out just in the pouch.
But remember, dry tobacco doesn't mean bad tobacco!