It seems confusion between "periodic inspection" and "general maintenance inspections" exist - the REGs are clear general maintenance inspections are at intervals listed by the manufacturer.
(1)A person carrying out maintenance on an Australian aircraft must ensure that the maintenance is carried out in accordance with the applicable provisions of the aircraft’s approved maintenance data.
Penalty: 50 penalty units.
Note: Regulation 2A sets out what is approved maintenance data for an aircraft.
2.3 A periodic inspection must be carried out on a private aircraft
within the period of 1 year from:
(a) the day on which the aircraft’s current certificate of
airworthiness was issued; or
(b) the day on which the most recent general maintenance
inspection on the aircraft was completed;
whichever is the later.
2.4 Subject to paragraph 2.5, a periodic inspection must be carried
out on a class B aircraft that is not a private aircraft within
whichever of the following periods expires first:
(a) one year from:
(i) the day on which the aircraft’s current certificate of
airworthiness was issued; or
(ii) the day on which the most recent general
maintenance inspection on the aircraft was
completed;
whichever is the later;
(b) the aircraft has been in service for 100 hours since:
(i) the aircraft’s current certificate of airworthiness was
issued; or
(ii) the most recent general maintenance inspection on
the aircraft was completed;
2.6 In this Part:
general maintenance inspection means a regular inspection
and check of a class B aircraft, its systems and components
that:
(a) is required by the aircraft’s maintenance schedule to be
carried out at regular intervals; and
(b) is not required to be carried out before the aircraft’s first
flight on each day on which the aircraft is flown.
private aircraft means an aircraft:
(a) that is a class B aircraft; and
(b) that has a maximum take off weight of 5700 kg or less;
and
(c) that is only used in private operations by:
(i) the owner of the aircraft; or
(ii) a person to whom the owner has provided the
aircraft without receiving any remuneration from the
person.
2.7 Unless otherwise indicated in the table, where the table
requires a thing to be inspected, the inspection is to be a
thorough check made to determine whether the thing will
continue to be airworthy until the next periodic inspection.
4.2 The time-in-service between Periodic Inspections is to be 100 hours aeroplane time-in-service or 12 months, whichever is the earlier, and for aeroplanes below 5700 kg engaged in private operations this inspection may be performed annually irrespective of hours flown. The completion of this inspection, along with any defect rectifications performed as a result of this inspection, is to be certified for in the aeroplane’s log book.
CAAP 42B-1(1.1): below
6. Periodic Inspection Schedule 6.1 The replacement or overhaul of time-lifed components required in an Airworthiness Limitations Section of the aeroplane’s maintenance manual and any special techniques required by the manufacturer or an Airworthiness Directive are required to be complied with. If it is clear from the terms of the manufacturer’s requirement that the manufacturer considers compliance is optional, then that requirement is optional.
6.7 Except where otherwise approved or directed by CASA the procedures and limits prepared by the aeroplane manufacturer are to be used when performing an inspection required by this schedule.