Frankly, I have an allergy to the idea that local events are always a major factor in travel planning.
What is the real change for most people?
For a business trip, the presence of a jazz festival in Montreal does not affect the travel decision or dates, even if hotels are more expensive.
It is a budget constraint, not a decision-making engine that changes the cash flow of the project.
Such advice is often just media hype for travel guides.