Usually yes but not always. A few years ago I went to a sale in my neighbourhood around noon or 1:00pm, I ended up finding a Super Famicom with a floppy based game copier along with floppies, a Game Gear with several games(imports from what I remember), an original Gameboy with some games(possibly imports too), and a modded PS1 with a bunch of backups. All for $20. I have no idea how it was all still there by the time I got there, but I was happy and carried a large box with it all back home as it was that close. The Super Famicom just needed a new video cable, although I still haven't tested the portables yet so they might be broken. It was pretty early in the year for garage sales so that might why.
Also if a place doesn't unpack their boxes properly you can still find stuff. I went to one place maybe around 10:00am and found out they sold a bundle of Atari 2600 stuff right at the start, but I managed to find an original Gameboy with a handful of games for $2 that was buried in a box full of random junk.
I went to one sale in my neighbourhood maybe last year that was advertised as a video game garage sale, all of the flyers basically made it look like it was from a professional dealer. I still went a bit late but managed to find a handful of N64 games for $5 each, and an Xbox for like $10 but it came with the High Definition AV Pack, I think a couple of cheap Wii games too. It seems most people avoided it thinking that there wouldn't be any deals because the ads made it seem like a dealer, but it was just somebody getting rid of his games which were mostly Xbox, 360, and Wii stuff.