A radius drawn from Maplewood spends money in three counties and two states
Circle targeting ignores every boundary that actually governs whether a click turns into a truck you can bill.
Draw a twenty mile circle from a yard near Maplewood and watch where it lands. Part of the City of St. Louis. A long list of St. Louis County municipalities. A reach toward St. Charles County. Depending on the radius, the far edge starts picking up the Illinois side.
Those are not variations on one market. They are different governments, different permitting practice, and in the case of the Metro East a different state. The clicks cost roughly the same and they are not worth the same.
Replace the circle with a list. Target by municipality and by county, group the ones that behave alike, and set bid adjustments where drive time and administrative variation change what a job is worth to you.
The immediate benefit is not efficiency, it is visibility. Once geography is listed rather than drawn, your reporting finally shows which places send work worth having, and that answer usually surprises the owner.