9/9 here as well, but I've always been good at those. 6 was definitely the one that took the longest for me.
My strategy is much like others I'm sure, but I essentially took something like this approach. I'd look at a center block on the first one and fold 2 or 3 blocks down around it, see how they would relate to each other, and then fold the other boxes around the same center block. If all 4 matched, I'd pick another center block and repeat. 6 was the hardest for that because of the fewer symbols with two each, and that the configuration where the arrow (I think) was out of place required the most "folding" to verify that. It is easy to fold one block down on each side and check the arrangements (at least for most of us), but when you have to fold something like 4 times to get the final placement, it can get a little confusing.
The 3 hearts one was probably the easiest for me.
Not being sexist here, but it is my understanding that women are much worse at imagining 3-dimensional rotations in their heads (which relates to them never having a fucking clue where they were going in MMOs...seriously, we all knew those chicks, right?). I'd love to see the results based on both age and gender.