Search anything with "near me" and Google answers with a map and three businesses. Those three slots are where local demand goes.
For local searches, most people never scroll past the map. They see three businesses, glance at the star ratings, and tap one. Everything below that block competes for the leftovers.
Google weighs relevance, distance and prominence. Distance you cannot change and relevance is mostly a matter of filling out your profile properly. Prominence is where reviews live, and it is the only one that responds to weekly effort.
A shop with 300 reviews and nothing new in eight months loses ground to a shop with 90 and four a week. Momentum is part of the picture, and it is the part a QR code at the counter is good at producing.
Steady beats large. Four a week for a year outruns a burst of forty.
Look up your category with "near me" from a phone that is not signed into your account. Note the review counts of the three businesses in the map. That number, plus a trickle that never stops, is your goal. Nothing about this requires an agency.