You bring up an interesting point. New York City is a People Meter market (PPM) which logs actual listening versus counting on someone making an entry on a form in writing.
Even more important is the number of signals in the market. Chances are there are several stations after the same group/demographic. If all stations after that one group did commercials at about the same time, there would be no competitive edge. However, moving commercials to different times, designed to attract the other station(s) listeners, give you an edge. In one market I worked, I moved our breaks up 5 minutes so we would always be back to music when my direct competitor went to commercials. For example, I moved my :22 past commercial break to :17. My competitor did their break at :20.
This might be the reasoning behind the non-standard times for commercial breaks.
There are always exceptions. At one station we did 10 in a row starting on the hour. Our first commercial break was about :40 and we had another at :48 and :56...4 minutes each. I even worked a station that ran 6 breaks an hour

08, :20, :25, :38, :50, :55) but only ran one commercial per break. They actually made lots of headway because they broke the habit of listeners tuning to another station when the commercials came on. The regular listener knew we would be back to music in 30 or 60 seconds so they'd stay with us.
I would say most all demographics are pretty much slaves to the clock in some form. Most events begin on the hour and the goal is to arrive with minutes to spare. Almost every activity is scheduled around the hour or half hour. If you are heading somewhere you tend to leave on the hour and half hour. The point I'm trying to make is no matter the demographic, people are stuck with a clock and set times, leaving radio to do better in number of listeners at certain times in the hourly clock. I don't know the demographic changes that.