If they were taught how to fly properly they wouldn't need a an ASI.
Set the correct attitude trim the bugger and let the aircraft do the work. To many pilots chase the needles instead of letting the aircraft do whats its design to do which is to fly.
If I had a pound for every student/FO that i have told to let go of the controls for suddenly all the turbulence to disappear, the aircraft start tracking in a straight line and for the airspeed to become stable I would be a rich man.
Instrument approaches require a bit more point and power. Visually its over controlling which leads to speed instability in the majority of cases.
My current machine is a 10 tonne TP with 3300SHP on the wings and I fly it excatly the same as a tommahawk on approach. I have a Vat range of 10 knots. But I don't need to worry about it cause its exactly the same picture whatever the weight because your flying an approach angle of attack on the wings. Set the picture, power as required to keep the decent profile and bobs your uncle the speed is right.
Please note flying on instruments requires more of a point and power technique my comments only refer to approaches flown visually.