Life sometimes throws financial curveballs at you, and many people don't have enough emergency funds saved up to deal with unplanned expenses. Sure, you could pay with a credit card and pay it off with interest, or go to the bank for a personal loan, or borrow from friends or family. What if you didn't have to do any of that?
The advantage of stacking precious metals is not only as an investment and store of wealth, but the chance to be your own bank. If you have hundreds of ounces in silver and gold, you don't need to take out a loan. You already own real money. You can go online or to your local coin store and sell a portion of your stack to pay for these expenses yourself. Sure, you are selling off some of your holdings, but you can always purchase more bullion when you have extra funds available.
If this type of emergency/wealth fund sounds like something you'd like to do, it's important to strike a balance between stacking for weight and having liquidity. While you'll certainly pay less premiums on large coins and bars, it's also a good idea to have some smaller denominations for when you only need a small amount of emergency funds. You can easily sell a stack of 10 rounds or a 10oz bar if you only need around $200. This way you're not stuck selling a kilo silver bar because that's all you bought to avoid higher premiums.
Whatever your goal is, make sure you sit down and write it out on paper and make sure it works for what you need. Keep it handy to refer back to when you need to use it, and make sure others in your household are on board with it.