If you don't always cook from scratch is there anything or are there some things that you absolutely must always cook from scratch?

I’m not much of a cook anymore but when I make lasagna I always make it from scratch, including the sauce and I even make my own noodles. Needless to say, I don’t make it that often. And when I have popcorn, I pop it in a big heavy pot on top of the stove so I know that the only things in it are popcorn, butter and salt. Plus it just tastes so much better than microwave popcorn.