One of the classic student mistakes in IF is 'instrument chasing' where any one or two instruments are concentrated on to the detriment of the AI - it is obvious to the instructor and will inevitably end up with inaccuracies or unusual attitudes as the task gets more demanding.
A good instrument pilot will base his scan around the AI but we all get lazy sometimes, especially when the workload and arousal levels are low.
When things get gnarly then it is those with the AI centered scan who will retain accuracy and safety and the instrument chasers will probably scare themselves.
Despite VF's dismissal of its value, the use of the AI for mountain flying has long been taught in the UK mil - perhaps because the skills learned from a visual/IF balance are even more important when you fly the mountains at night.