In my experience, owners at a general meeting can vote to allow a strata committee (and by inference the strata agent) to spend say up to $500 (in the forthcoming year) per event without being required to hold a formal strata committee meeting, let alone an OC meeting to discuss the matter or consider quotes.
As to the mechanics of work being done, either one person on the strata committee can be delegated with the role of giving the agent the instruction to do the work or the issue is brought to the attention of all strata committee members, even by email and a majority must be in favour of the work being done before the agent is instructed.
Neither approach removes the requirement of the SC from minuting the expenditure retroactively, as kaindub states.
While such a cap, say $500, may work well for situations such as an emergency, many expenses I have seen are not urgent and I would be suspicious of any situation where the entire strata committee was not informed of an expense prior to it being incurred and allowed to express their views to each other, even by email, before instructing the strata agent to go ahead or not.