When a furnace dies, a pipe bursts or the power goes out, homeowners search on their phone, look at the map and the reviews, and call. The first company that answers, and sounds like it can help, usually wins the job. Everyone else paid for a lead they never got.
Demand also swings with the weather and the seasons, so marketing has to scale up for the rush and keep the schedule full in the slow months, with maintenance plans, past customers and referrals.
Most contractors don’t lose jobs because of weak advertising. They lose them to a dated website, a thin Google profile, a missed call at 7 pm or an estimate nobody followed up on. Fix those first, and every marketing dollar goes further.