What's so surprising about QFIs being different. I reckon I helped the good students to be better but wasn't the best for the weaker ones.
If you passed your IRT with me you would never have a problem with instrument flying.
Remember having a good average student who would lose interest after a few minutes during formation flying and drift out of position so we were about to die. No success with him (despite hitting bone dome several times) but a quick couple of trips with someone else ( a creamie) sorted him out.
As a student on JP1s and Vampires I had very good, pleasant instructors but the QFI I remember best was the feared MP Evans. We were all getting a bit sloppy towards the end of the Vampire course so check flights for all. "What height are you meant to be boy? 1100 sir. Well why aren't you" I was at least 20ft out. Same with the speed. If you can fly at 152 when you are meant to be at 150, why aren't you? That stuck with me for the rest of my career.
When I was a QFI there was a bit of a shortage of pilots so we were getting some pretty poor ones through the selection process. They needed to be weeded. As for the Middle Eastern ones that's an epic tale, 30 hours to solo on a JP. The Russians had never let them get beyond taxiing part 1. The very odd exception, one from Kuwait who came top of his mixed course. Leading a pair of I....is solo formation more than one QFI was heard to boast that they had never caught up.
Remember as an IRE before I did CFS having a new arrival, first tour, as were we all,for his IRT. He was good and then would switch off completely and give up during unusual attitudes. New squadron commander not happy at failure. This guy had already been brown-nosing with boss.
Neil Williams suggested he have a ride with him. Trip went well until start of a BABS approach when idiot pilot trims full nose down but has forgotten that's what you do after lowering full flap in a Canberra which he has omitted to do. Even Neil chickened out of this Stuka approach. Should have been chopped in training but survived a full career in flying. Luck, or were we wrong?