Planning fundamentals
Seasonality
Seasonality is the predictable variation in demand, media costs and competitive pressure across the calendar: retail peaks, travel booking windows, B2B budget cycles, Ramadan, summer troughs. Plans that ignore it buy expensive attention when demand is elsewhere and miss the windows that convert.
In practice
Seasonality affects both sides of the equation: audience demand rises and falls, and auction prices move with competitor spend. The same budget buys very different outcomes in different weeks.
Good plans encode seasonality in the flighting weights, so pacing and evaluation respect the intended shape rather than punishing it.