Why I Have Five Times as Much Pasta Sauce as Spaghetti

For a start, I shop without a list, and usually without even looking around to see what I need.  I don't even use the other popular method: call someone at home and ask what to buy.

I've never had a problem with quickly-used products like bread.  But those intermittently-bought items are a problem.  I've noticed a cycle I go through:

1. In the grocery store, I see Item X, and can't remember whether I need it.
2. Reasoning that since Item X takes a long time to go bad, I decide to buy it anyway.
3. I get home and realise that I already had some of Item X, but figure that I'm better safe than sorry
4. This happens several times, until I have a comically large supply of Item X.
5. Now when I see Item X in the store, I don't buy it, thinking of the bursting cupboard full of Item X at home.
6. Again, this happens several times, and I get out of the habit of buying Item X.
7. I slowly use my supply of Item X, until I run out.  
8. In the grocery store, I see Item X, remember that I've run out, so I buy it.
9. Go to step #1

Spaghetti is the big weakness in all this, since both pasta and its sauce go through these cycles, and somehow, they're never in sync with each other.