You can either spend YEARS cleaning up after repeat offender vandals (copper wire thieves who do thousands of dollars of damage in a night to get maybe $100 or some new “artist” who has been encouraged by the NY Times, Vice Magazine, MTV, Museum of Modern Art, etc.) night after night after night after night after night or you can be done with it.
Lock the turds up and throw away the key. It isn’t a phase and it isn’t a wave of activity by hundreds. A handful of habitual repeat offenders. Lock them up.
Here in Australia we actually have a database of tags/graffiti - anyone can take a picture and it be filed with the Police - when the offender is finally caught they can face prosecution for each offense as their tag is their ID. So here long term taggers - especially once over 18 - if caught can do a fair stretch in the jug as their damage cause can easily be in the tens of thousands of dollars - Having a database has made a remarkable difference in the amount of graffiti.
Underage offenders may spend some time doing public service - like cleaning off graffiti or parks and gardens.
As I work in Security and tend to be reporting this sort of stuff I would confidently say that since the recording of tags the Grafitti rate would have more than halved and I think I am being very conservative there!