Done mine on 2:1 ratio, was great. I think id find driving for long periods trying to concentrate on how to drive for the test really difficult.
We done 4 test routes per day, 2 each with some reversing and coupling at the end of each day. was great,
if I done first route then could jump in and watch the next guy with less pressure and actually take a bit more in then visa versa. on one of the days the other fella couldn’t come in to the afternoon as he’d a funeral,
I done 2 routes back to back and was mentally draining and found myself making stupid mistakes. Instructor pointed out to me that on the test it’ll be one route and he feels thats the most he likes you to do in one go and to be fair after that I agreed with him (even if he was just trying to make me feel better bout a not great 2nd drive!)
Anyway, got through the class 2 and class 1 both doing 2:1 not a bother at all with the same instructor at the time