Nothing else on this list works this way. The treatment being quoted is a single afternoon, but what's actually changing hands is a place on a route, billed quarterly, for as long as the customer stays. Acquisition cost that would be indefensible for a one-off service is comfortable here, and a company that measures it against the first invoice will always reach the wrong answer about whether advertising works.
Demand is triggered rather than searched. The first genuinely warm week, a termite swarm on a porch, mice moving indoors when the nights turn. Each one produces a wave of people who weren't in the market the day before and who will book with whoever they find that afternoon. Those triggers are predictable enough to be ready for, and most companies are still writing the ad after the phone has already started.
Then there's the part nobody advertises their way out of. Cancellations decide whether any of this paid, because an account that leaves after the second visit cost more to win than it ever returned. The months between treatments are where that gets decided, and for most companies those months are silent.