Historically, the following is true:
- Flights are the most expensive within 2 weeks of flying
- Booking trips more than 3 months in advance is typically cheaper
What I have seen in 2022-2023 so far? Since the airlines have no problems filling their planes, there are very few sales, other than to get you to buy vacation packages (which have more profit).
Southwest *might* do a sale to try to get back some goodwill after their issues, but if they are flying mostly full already, there is no need.
Just remember, in the 80s, flying was even more expensive.