Many owners check a single phrase such as their service plus Dallas, see a decent position and assume the job is done. Meanwhile, customers in Plano, McKinney, Garland or Grand Prairie search from their own neighborhoods, and Google answers them with businesses that sit closer or explain their coverage better. The metro is wide, and proximity weighs heavily in local results.
Two cities, one sprawling metro
Dallas and Fort Worth share an airport and a media market, yet searchers treat them as separate places. A firm with its main address near Las Colinas may win Irving searches and barely appear for anyone west of Arlington. Mapping where your real jobs, patients or accounts come from is the first input for every later decision about pages and links.
Suburbs that search like cities
Frisco, Allen, Denton and Mansfield grew into places with their own restaurants, clinics and contractors. People there type the suburb name, not Dallas. If your site only mentions the core city, those queries go to someone else.