Thank you for putting it that way. I swear if the rest of the world just poked fun at us for using it, we would probably change it. “Awww look honey, the Americans are still using miles and pounds, isn’t that precious..”
I have a habit of measuring ground distance in meters, for example, because I was in the (US) Army and yes we measured those things in meters/kilometers. But other things are not measured like that.
Measuring systems are only useful if they are, well, easy. And some systems are more easy in certain circumstances than others. Which is to say, it's easy to get used to a meter being a pace (tie a meter long string to your ankles).
Anyone have a rhyme for it?
It's really not. Most of the time, I just convert to grams and use a scale so I can get an actually accurate input quantity. I don't want to think about "heaping" and "leveled" and "packed" and different densities, humidity or uneven distribution within a measuring implement. If I'm going to be putting it on a scale I'm definitely not setting it to ounces.
When was the last time you really looked and said, geez, thank the lord I can divide 1lb 14oz into eights really easily in my head?
On the math thing, probably during Christmas when we were trying to stretch a baked French Toast recipe to feed 9 people in stead of 6. Worked great.
My french toast is ruined! I measured the exact amount you said! Not realizing that the original cook was using the Larry David measurement system. "Ehhh that's close enough".