Two rates decide everything
Recognition accumulates through exposure and disappears through movement and forgetting. If the second number is larger, the position erodes no matter how good the creative is or how much reach the report shows.
Once it is written down as a rate, the awkward questions become answerable. How much presence is actually maintenance, what a pause really costs, and whether last year's spend held ground or lost it quietly.
Word of mouth leaks at the same time
A referral network is made of people, and in a high-movement metro those people relocate. The neighbor who recommended you in Mueller three years ago may be in Round Rock now, recommending you to a different set of households or to nobody at all.
So the referral base needs replenishment for the same reason the recognition does. Businesses that assume word of mouth is permanent tend to discover otherwise about four years in, with no clear cause to point at.
Arrivals are the cheapest recognition on the market
Somebody who moved in last month has no incumbent to displace and no local name they trust. Reaching them costs a fraction of what it costs to change a settled household's mind, and the window closes within weeks once they have chosen providers.
That is why weighting toward arrivals is not a niche tactic here. It is the only part of the market where recognition can be bought at a discount, and this metro produces it continuously.