NVQ seems to teach to an exam pass, rather than actually learning anything technically. Being onsite, and learning from the ground up is more practical, and useful, but learning to pass an exam?
The NVQ assessments , are all carried out on site nowadays. Around 10 -15 yrs ago they could do them in college using simulation (ie, hanging a door/doing a traditional roof etc would be done in college on specially built rigs).
I did the D32/33 assessors qualification (that's more about knowing how the system works than assessments)
College assessments were easier to do than site ones. At least you could keep dry and warm whilst doing their assessments.
Must admit though, some students struggle with the theory rather than the practical, probably because they are working on site more than they are in college. Theory is just the underpinning knowledge bit. I once asked a student why do we cut birdsmouths on rafters on a traditional roof !! The answer,, "Because the college lecturer says so !!!"