OH I still need to get my rock painting on! With everything going on of late I have totally not even started. When I go run to the store to buy Yuan more cat food, I will keep a look out for some good rocks to paint. :D
I love your choices of hiding spots, especially a tree rock in a tree. I once left a painted rock under a tree that I knew often homeless folks sat under for shade, that was near some errands on the way there. By the time I had done my shopping and was walking home, it was already taken. :)
On the flipside, when I made some magnets, I learned that people are often not very observant of what they are walking past. If I put them on a pole with a crossing signal button on it, they got taken, as pedestrians and cyclists were stopping there and looking to push the button. If I put it on the sign from a doggie waste bag dispenser, a bus shelter, or a handrail, they also got seen and taken. But I tried one on one of those big electrical boxes right next to the sidewalk and it sat there until it was so damaged from getting snowed on that I brought it back in for repairs. I guess people are just not paying attention to those. xD
Well, you've had more than plenty of life events as of late, so I think we can give you a "hall pass."
The best spots seem to be where people have to "pause" for some reason, whether it's to sit on a bench, wait at a bus stop, crosswalks with lights or something similar... or parks, where people are less "busy" in their heads.