Most working agents specialize by developing repeat familiarity with a set of neighbourhoods where they list and sell often, tracking recent comparable sales, buyer patterns and pricing quirks specific to those pockets, rather than spreading equally thin across every area of the city.
If your target is a neighbourhood outside an agent's usual range, ask directly how recently they closed a sale there and what comparables they would use, since a confident answer with specific streets beats a general assurance that they know the whole city.
The right question is not how many neighbourhoods an agent covers, but whether they know yours. Get your hand-reviewed valuation from Joel Dyck.