Tampon Purchasing Strategy

One day I ran out of tampon when I exactly needed them. I had to go to a store specifically for two packages of tampon, spending about 1 hour. 

So every month predictably I will need about two packages of tampon, and the tampon brand/type I am using is the same from my favorite brand, so it seems obvious that buying tampon every month is far less efficient than purchasing large stock of tampon for extended period of time ( one or two years).

Then I remembered in "Big Bang Theory", Sheldon advises Penny to buy 30-year worth of tampons because "there are a lot of advantages to buying in bulk" and "Tampon is a product that doesn't spoil and you are going to need them for at least the next thirty years". Then of course Sheldon requested Penny's mom's age of menopause to better estimate how many years of tampon to buy. 

Apparently buying 30-year worth of tampons is not the best strategy because of: 1. the large space they take and the trouble to move them around for 30 years. 2. improvement of tampon technology over the years. 3. simple boredom of using the same product. 

But Sheldon did have a point. In my mind buying in one or half year of a stock when it's on sale seems to be the best strategy. 

(And I admit that here I am just trying to be nerdy and funny by playing with the semi-taboo topic of "tampon" using my female perspective)