I think that getting 'good' fares is now a lot of luck. Whether you are planning to travel in 11 months or 2 days. The airline booking system now has so many variables of which you can have zero knowledge.
- School holidays
- Special concerts/events/conventions at destination
- Planned promotions to reduce prices at one point in the year will push them up at others
- Compettion on the route
- Aircraft capacity, including planned maintenance
- Fuel price
- Staff disputes
These factors can vary by the week, the day, the hour. So, whilst there used to be ways for pax to double guess the airlines, now there are not.