Paddy,
Normally a strata manager will rely on the EC authorising the Treasurer to approve invoices, however, the EC should be authorising the spend initially, making the decision whether or not to do the work or accept a quote.
Depending on how big a job or the nature of the issue, the EC may approve these works via a quick discussion or may require an ec meeting.
For example, fixing a leaking or burst pipe is something that hopefully the ec will move swiftly on while painting common property internal or external may involve getting several quotes and referring to an ec meeting or a general meeting depending on availability of funds.
This is in many ways dependent on the OC’s corporate governance and agreed approach and also any limitations the OC placed on the ec at the AGM.
A good strata manager should simply be the agent to act under the OC/EC instruction.
Mr S