Targeting
A radius that's too tight (say, 3km) can genuinely restrict Meta's algorithm from finding enough people to optimize against, especially in lower-density areas — you end up paying more per lead simply because the pool is small. A radius that's too wide (50km+) risks generating leads from people outside where you'd actually travel for a job, wasting your time following up on unbookable leads.
A reasonable starting radius for most tradies is 15–25km from your base of operations, adjusted for how dense the local population is — a tighter radius works fine in a dense metro area, while a rural or outer-suburban business often needs to go wider just to reach enough people.
Donded's onboarding sets this from the service radius you provide when setting up your business — worth revisiting in Settings if you started with a rough guess and now have a better sense of how far you're actually willing to travel for a job.