What times do you usually detect?
I have found that evenings are starting to get more and more difficult with the days getting shorter. As it is right now, I go out after dinner and get about 2 hours in before it is so dark I can't see what I am digging. I figure that, once dinner is done, some parents will take their kids to the park or let them go there for a short bit before bed, or before it gets dark. Usually about 7 or 7:30 from what I have noticed. It won't be long though till 7 will be too dark in itself. I haven't had much trouble with the kids in my area. So far, at least. The last couple times out, I was out about 20 minutes before some kids came up to the play lot. It was about 7:30. The older kids, pretty much, stay away, A couple guys came up and asked if I was finding anything. I said, a few pennies, some foil, then shrugged my shoulders. They then went and litterally hung around on the jungle jims to chill out from playing some lacrosse. A couple girls just sat up on the slides and shelter area till I left the swings, They then came down and sat there chatting much of the time. Another time, a family came out, again about 7:30 or 7:45. They stayed about 20 minutes. The girls played on the swings causing me to have to pass on about 5 that I was searching. No problem though, there were another 10 in another row accross to still search. Their little brother just stood there and watched as I tried to locate and dig a couple targets.
I am starting to find that evenings are running out. By the time I get out, there is no avoiding that time when kids make their last dash for the play lots. And, as I said, it won't be long before it will be dark then anyways.
The best time that I can actually think of, would be from about sunrise to about 9am. That would be for the public parks away from schools. I would never go search at a school when kids are present during the school year. We don't have the lock down issues here but, when teachers and administrators are present, during the normal work day, would not be a good idea. Note that some schools also allow themselves to be a safe haven, so to speak, for kids before and after school. As long as adults are present, I would consider school to be open and would stay away.
I figure that for the preschoolers and such, by the time the mothers get them up, dressed, fed, get themselves off to work and leave the kids with their nanny or grandma... it will probably be about 9am before they make it to the parks.
I have been thinking of my opportunities once the summer ends. I would consider the school lots off limits due to the school day or darkness. Public parks early in the morning might be good. The beaches after that. Seems that people don't go to the beach much during the day when school is in session. They are either working or in school. Those that aren't are probably adults with their own interests to keep them from thinking about what I am doing. I went down there, a few times in May and found that about 1 to 3pm were good. After that, some kids probably head down there some. Mid day though, The only people I encountered were people picnicing on their lunch hours, taking a walk or little jog along the water, walking the dog.... catching a breather between housekeeping and when the kids get home. Some of the county forest preserves around here could also be good in the middle of the day. That is assuming MDing is permitted. Haven't really looked into it.