Sophomore year of college I had a debate with my roommates about how to correctly make a peanut butter & jelly sandwich. They all made it by putting peanut butter on one side of the bread only. I made it by putting peanut butter on both sides of the bread. I thought they were crazy as I had always put peanut butter on both sides. They ended up singing the peanut butter and jelly song to prove to me that they were correct.
I am unsure if it was my mom who taught me to put peanut butter on both sides or if I started doing it on my own. If I eat my sandwich right away I try to remember to put peanut butter on just one side, though remembering in time is nearly impossible for me. I always remember after I've spread it on both sides. But whenever I might have to wait to eat the sandwich and it has the chance of sitting out for a while, I still put peanut butter on both sides as it keeps my bread from getting soggy. I would do about anything to never have to eat a piece of soggy bread again in this lifetime.