I've played Catan with cards instead of dice- you have 36 cards, each with a number that can be attained by rolling two dice. How many times a number appears in the deck is its odds of being rolled. Statistically, you will roll 7 6/36 times, so there are 6 sevens in the deck. There is only one 2 and one 12 because their odds are 1/36. You shuffle the deck, and draw a card instead of rolling (once you go through the deck, you just reshuffle). This means that luck plays into when you will get a resource, but not if you will.
Flattening the bell curve can help a good deal, but the only way to guarantee that you get a resource each turn is to redraw until you hit a match with one of your settlements... unless I'm misunderstanding you.
edit: NM, I misread your last sentence. I've never seen a territory run dry for the whole game, but this would indeed prevent that.
