My jars usually seal themselves... You'll hear them if you are anywhere close by! I don't know if it is a change in temperature or air pressure but it always happens. It takes a bit of effort to pry open the seal again.
mkvillaire,
If you do it this way, IMO, you will always be smoking your tobacco at its peak.
I am convinced that the longer you have a tobacco opened, there's an evaporation/dissipation of flavour compounds and oils along with moisture. You can rehydrate old tobacco to make it smokeable again, but it'll never be the same as the new stuff and I think there's a good reason for it!
If you have an aged tobacco, especially, I think it's best to smoke through it as soon as possible because that goes downhill fast.
It goes hand in hand with getting a better appreciation of the blend by smoking it until its gone - you catch the tobacco while it's still dressed up in its finest, not when it first crawled out of bed in the morning...
Again, I was pretty strict with my initial conditions, but their effect will vary with individual habits...
Somebody who smokes 1 or 2 bowls a day could probably smoke that way for a very long time.
Somebody who smokes 5-10 bowls a day would most likely get bored along the same lines as Jud's analogy - scrambled eggs for every meal.
On the other extreme, you have people who smoke the one blend for the best part of their entire lifetime. Most famously among these people are the mysterious "old codgers" we all speak of... I honestly don't know if I would want to be that loyal to a blend, but I think we all would do it if that was our only option...
LoTPR, I am sure you see the benefits to both approaches - variety and consistency. The main difference is that you "know" a blend much faster when you stick to one for an extended period; it's like taking a crash course. lol.