I think many of the busts in sim come down to poor BI which goes back to instrument instructors.

Ok. I’m going to say it. Most CFII’s suck. I mean really suck and do more harm than good.

Instrument flying is almost like playing a musical instrument or sports. A music teacher does not introduce complex pieces until a musician can do the basics. Scales, after scales, after scales.
There is a reason good coaches work so much on basics. There is no point in even scrimmaging if your players can’t cradle and lacrosse stick or dribble a basketball.
It’s the same with instrument flying. An instrument student should not think about even tracking a course until they can nail a B pattern. Yeah, it’s dry and boring. 1,2,1,2 scanning. Pitch+power=performance. Over and over. Hours of it.
But when you become stressed, when you fly and aircraft that is bigger, faster, more complex approaches, that’s what you fall back on. The basics.
I don’t know how many times I’ve taken on students who had problems with instruments only to find out it was a problem with basics. Their instructor was introducing approaches before they mattered BI. We had to go back almost to square one.
So make sure you have it down cold before you go to an airline.