I had about 7 walking around wanting to see Rapunzel while she was doing a 24 hour task, and there were others at the same time. I had 10-15, definitely more than the 7 mentioned is the maximum allowed. Hadn't heard about the every 30 minutes thing, I really don't usually pay attention to how many are around at a given time! Just love that I started out on the top for the event because of this, I usually start and end in the 50-100 bracket, not the top 10 at any point.
I wonder if the game functions differently for different people playing on different devices? I have never ever ever had more than 7 wishes/happy faces walking around at the same time. Up until I have 7 new wishes will enter the game exactly every 30 minutes at the top and bottom of each hour. Once I have 7 no more wishes enter the game until I take care of one of the existing wishes/happy faces first then the next time the clock hits :00 or :30 a new wish is added to make it 7 again.
Maybe if you let your happiness drop below a certain level things change? My happiness is always over 85%. It has never dropped below 85% since I got to that level really early on in the game.
It would be nice to figure out why some people are able to have limitless wishes/happy faces and others are limited to a maximum of 7.....