It’s much easier to cut something in half and half again, to get 0.25 then it is to cut something in fifths to get 0.2, for example. So if you’re a proficient carpenter you have all sorts of tricks and geometrical constructions that let you work quickly without necessarily making a precision measurement or taking out a measuring tape.
Imperial gets tricky real quick as soon as you need to mix additions/subtractions with multiplication/division which happens surprisingly often in building.
eg: imagine you have a 5 & 1/2 foot cabinet with 4 equal sections framed out with 3/4" boards, what is the height of each section? It's (5 & 1/2' - (5 * 3/4")) / 4 which I guarantee nobody is working out in their head easily.
