Different approach than yard sign farming, but it's worked well for me. I put a small branded sign on every client's lawn after I treat it — costs about $1 each. It's not about flooding a neighborhood, it's about visibility tied to real work I'm already doing.
Every year I pick up new clients directly from neighbors seeing the sign on a property nearby. It's essentially free advertising since I'm already there doing the job anyway.
The branding part matters too — if it's unbranded, a neighbor seeing it has no way to find you. Mine has my business name and contact info right on it.
I'm curious about the strategy you're describing though — putting signs on busy streets or near community mailboxes until they get pulled. Has anyone had luck with that versus just sticking to client lawns?