Or we could call this le cul entre deux chaises...
I've been baking a lot, especially lately. Most of the recipes I use are American, many even from the family cookbook compiled by a distant cousin years ago (an absolute treasure that cookbook for many reasons - excluding velveeta and cans of cream of mushroom soup). Which is fine, I have a set of measuring cups and spoons. But for some things, like butter, I have to convert. Butter is sold in rectangular blocks here, not sticks. So a half of a cup of butter, a stick, has to be converted into grams, (it's about 120 grams, by the way) and then I have to weigh it on my digital kitchen scale, which is also fine, it's just something that has to be done.
Because that's what happens when you live with your ass between two chairs. You do what is necessary to keep your ass right where it is and not lose your balance.
You integrate the conversions as you make them, building a database of duality. Sort that.
Which two chairs are you sitting on?