my driving instructor was a boss to be fair!! nice tidy guy, gave good instructions, always went through things to make sure I understood. If I screwed up he would let my know I had done and then go through it with me there and then or when safe to do so, on the rare occasion I would make a bad mistake he'd really let me know!!! did come across as harsh sometimes but hell... it worked! never made those mistakes again hehe

one example was on a dual carriageway roundabout I was heading straight on and as I was about to come off I left it a bit late so was doing more of a left turn into the exit and this white van driver who was joining from the exit i had passed (one i didn;t want) just floored it behind me and tried to like undertake me because in my own fault I was straddling both lanes

... but as I was turning!!!! so we both came to a stop and the white van man started shouting and I was a bit shaken but my instructor wound down the window and gave the guy an earful about how retarded he was being, seeing as i'm clearly a learner driver and he should expect some unpredictability and give more space, also that he was trying to undertake even with us signalling to turn off.. xD
then on massive roundabouts (like 4/5 lanes where there's motorways and A/B roads) I wasn;t great at reading the signs so we spent a lesson or two just doing lots of round abouts from different directions and I soon started to own them
then day of test came along and I passed with 1 minor for hesitating at a round about because there was a massive lorry coming and I thought not to try and push it so got marked down for "waiting" hahaha (on the way to the test center we almost got sideswiped by a going all around the round about in the outside lane

)
one of my friends had a bad instructor... she was learning but he kept doing the same stuff and not progressing onto anything... like she had a fair amount of lessons but hadn't done a single maneuver yet?! and pretty much doing exactly the same route and she said she wanted to do more but he insisted no... she then got a new instructor and passed shortly after

I also took her out for a few lessons and she even said I was a way better instructor than he was xD woop woop \o/