The work sheets for Sched 5 have been around forever even before it was called that. The intendant use was that is was for aircraft that didn't have a maintenance sched in the m/m. Its success has brought about its own undoing as everyone has adopted it as mainstream. That's why it has Ag floats aircon etc already listed. At the end of the day is just a guild to what has to be done its a minium amount of work that is required.
The addinion of what the manufacture calls up in chapter 5 for life components is what everyone is worried about
Now CASA don't wont that responsibility and will close the loop hole down for what of better words/
As for AC43 we always been able to use it if it was in the approved docs list in the M/M for the aircraft you where working on or if a repair was done via an EO by a car30 and he stated to use it.
When an aircraft is modified for its original state say a Raisebeck mods it come with its own M/M which is listed then on the LBS to carry out the maintenance IAW with it.
Now you can use the Manufactures sched and still do 50 hourlys all you have to do is change LBS.
cheers