It’s just a game of cat and mouse. I dont think there is a way to “win”, because it’s so easy to make new graffiti, and not practical to try and police and catch people in the act. I think they require private property owners to clean their own graffiti, which really sucks, but makes it more manageable for the city to focus on public areas.

The city really just has a queue of cleanup sites and priorities locations that are high visibility or important, like school yards or transit infrastructure. An elementary school nearby had its mural destroyed by graffiti, and it was cleaned up within a day.