Std IFR procedure is to fly a rate-1 turn and time it.
So note your heading (when straight and level); figure out how many degrees you want to turn. Then start stopwatch and start turning at rate-1.
This works a LOT better than trying to figure out a heading from a magnetic compass, and is the only procedure I teach IFR students.
That said, its always good to have the knowledge as to why you should not rely on the magnetic compass during turns/acc..
Yes that's the way I've taught it for several decades but that's not the point - you still need to start off and finish with a heading reference. Also Turn Coordinates/Needles are not always calibrated correctly.
Pilot's need to have an appreciation and basic understanding of compass errors - is it
really that difficult?