no diffrent from any other job requiring a mixture of skilled, semi-skilled and unskilled labour.

Do you get much unskilled labour on a building site? Not in my young day! You got a lot of pride in a job well done & well earned pay packet whatever the time-served skill. Sorry if this getting all a bit Auf Wiedersehen, Pet! (and I know I'm talking to a skilled spark) but you have an even more exacting cause for precision at all stages of the job in medieval Romanesque & Gothic architecture. Then as now - unskilled meant unemployed.