There are no requirements for the executive committee to hold meetings, although it is wise for the executive to meet during their year in tenure and the frequency will depend on the individual strata scheme and the issues that need to be discussed. Meetings are required when the executive needs to make a decision. A chat in the hallway or email to members does not constitute a meeting.
However, the executive committee must meet where not less than one third of the members serve a formal request on the secretary to hold an executive committee meeting (see Schedule 3 Strata Schemes Management Act 19996, in particular clause 7).