Usually Holiday weekends people are focused of the events the Holiday brings. For example Fourth of July, there is BBQ's and fireworks, Thanksgiving, is a family day. People cooking, or traveling to be with family. Labor Day is family outings. Usually a Holiday weekend is planned in advance and very few people will stop for a Garage sale.
I like to go to Garage sales on Sat or Sunday mornings when I have nothing planned. I will even look in the paper to map a route so I know where i am going and find the neighborhoods and advertised items I am looking for. I hope this helps Joan