Rodents can be very determined, however I do not store foodstuffs in areas that I do not check often and that my cats do not have access to. Good barn cats excel at rodent & snake patrol, and love to climb among food storage containers. I have more trouble with humidity, at least I did until I researched methods for preenting rusting on metals. A thin coat of food grade mineral oil keeps rust at bay, so my canned goods store at least twice as long. Six years and counting. I think part of the 'secret' to reliable food storage is not to put it away somwhere you never go, and never check on it or use it.
If you follow the basic tenet of storing what you eat, and rotate your stock by eating what you store, you can keep tabs on potential problems and prevent same while learning to use stored foods & keeping them fresher.
While it is true that not all foods store 20 years, those shorter-storing foods are simply rotated more frequently. Easy-peasy. Of course, it does help to have a recipe collection of ways to use those stored foods, and it helps to know how to cook under various austere conditions (it is fun to practice open fire cooking anyway) but some times I think folks are making it far more complicated than it needs to be (aided and encouraged by the food storage companies who are profit driven (and dont mind stretching the truth to get you to buy the more expensive storage items versus the common feed store grains or brocery items which cost far less. Packaging them in mylar with O2 absorvers is easy to do at home, and plastic bulk pails are readily available from wal mart among other places. (You only need FOOD GRADE if you do not use mylar or food grade liners) OK, I guess that makes me a cheapskate....so be it. I like my own cooking and recipes better than the pre-made freeze dried foods anyway, and I like knowing what is in those canned goods I personally put up. I can use the money I save for other preps, like traps or ammo.
To go back to the original question, I buy the bulk of my food preps at the feed stores (whole corn, whole wheat), grocery stores (shop the sales for converted white rice, pasta, legumes, flour, sugar, salt and the like), and only order mylar & oxy absorbers. The cost of shipping more than doubles the already high prices of pre-packaged storage foods and are not worth it for me. I have more time than money and will put up foods myself. We use plastic pails, the storage items with the pound down tops and oxygen absorbers; the currently being used foods are in gamma lidded pails, or in locking heavy duty totes readily accessible to the kitchen, and the actual in the process of being used goods are in 3 quart plastic jugs (cranapple juice jug, recycled) or in 2 liter soda bottles that handle and pour easily for cooking and they keep nicely in the kitchen close at hand. A serach of OLD cookbooks that actually teach cooking, not meal assembly, helped me to collect a base of recipes using the longest storing staples effectively (Oil, for example, goes bad a lot faster than solid shortening; sourdough will effectively make your bread making yeast last forever - I know, I kept some going for 6 months during a job layoff, LOL.) You can do a lot more than you think using basic grocery store pantry staples, so they are my biggest go-tos.