I say 10-6 because those are hours of normal business operation and that is time in which people expect noise and such around their home. I understand it is hot, and if you are polite enough to check in with or at least warn your neighbors it shouldn’t be a problem with anyone if you want to mow before or after that. I try very hard to make sure that I am not disturbing my neighbors and try to give a heads up if I am going to have a loud party or be moving furniture or doing something that could be disturbing when people are waking up or winding down for the day and I expect the same from my neighbors.
I try to be done before 9:00 p.m. or dark (but will go late if the alternative is to wait through an upcoming weather front and not be able to finish for another week and another 4" of bluegrass).
I have no near neighbors with small children or odd working hours. (Deb has the odd working hours–overnight on-call–and I will put off starting the job until she is up or called out for a visit rather than starting earlier and waking her after a night with four calls or something.)
When it comes to business hours, I say if the garbage truck can lumber through the neighborhood at 7:00 am, I can run a lawn mower.
I also think it’s a reasonable expectation that the neighbors are awake at 8:00 pm. I mean, how long does it take to cut the grass? People are way too sensitive. We just had a story on the news yesterday. A church bell has been sounding on the quarter hour until 7:00 pm since 1898, and two neighbors pitched a bitch about it, so the church is now stopping at 6:00. WTF!
For me, lawnmowing is fair game between 8 AM and sundown. Since I’m moving to a hobby farm this weekend in the middle of nowhere and my mower has headlights, I could even mow into the half hour of twilight, too.
Been there. Done that. Drunk. At midnight. Do not try this at home.
Midnight, maybe. Drunk, no. I don’t drink for medical reasons other than addiction. By definition, I’d have to do it at home… 
When I was there, Knowzones annoyed me so much that I went out of my way to violate them, and give them the proverbial finger.
Now that I’m in East Jesus NC, they don’t matter…