My understanding is that when the new 100.5 regs were introduced, it actually omitted compass swings. At the time of our last 100 hourly ours was done expecting that CASA would soon correct that.
100.5 re-introduces a range of periodic checks that were previously dropped as being not warranted. eg, fuel gauge calibration.
I did the exercise a while back of going through our log books and putting in a table all the calibration results for the key instruments over the aircraft's 30-odd year life. The main thing I leaned is that many LAME's can't calibrate for sh*t. With full trend data, some calibrations have clearly been just plain wrong. Watching our last fuel tank calibration, it was clear that the guys doing it didn't understand what they were doing . But to challenge it means another fuel drain and repeating the exercise which would blow another $1500. And our electronic fuel totaliser is more accurate anyway.
The other thing I learned is that most instrument don't change in calibration significantly. I challenge those supporting regular calibration to do the exercise.