Waayyyyy back in 1995 when you could go straight for a class 1 licence, i went for an assessment with a well known training firm and the instructor i got was a wee scrawny guy who ended up being a prick …
he told me the brakes on the truck were a bit sensitive so be careful and i told him iv’e never driven a truck, in fact the largest vehicle i had driven was a VW Beetle, but he said yea yea whatever lets go…
so we went out and i hit a few kerbs and ■■■■ me those brakes were sensitive, every time i tapped them, he theatrically threw himself at the dash which really annoyed me…
we got back to the yard and he told me to blindside reverse it between two cones and i reminded him that i have never done it before but it fell on deaf ears and low and behold i made a total mess of it so he told me to park it up and he bluntly said that i would never make it as a driver and go find another career…
this destroyed my confidence and for a couple of weeks i didn’t know what to do but i decided to try again with another training firm…
when i got there for my assessment i was given an instructor who was an ex army drill instructor and looked like he just came off the movie Full Metal Jacket and i thought oh no here we go again…
but he ended up being the nicest guy and his attitude was brilliant, he was calm and kept saying don’t worry about that every time i hit a kerb etc as he knew i hadn’t done it before and at the end he didn’t even bother with a reverse as he knew i wouldn’t be able to do it…
he told me that it was a decent drive for a newbie and it would take 4 days of training and a test on the 5th for me to pass and in the end he was right 
( so much for the scrawny prick saying i wouldn’t make it as a driver )
so yea having an instructor with the wrong attitude does make a difference 