I got most of them, well on both sides actually. That said, when they start getting rather fast, there is a question on how fast we can move the mouse, more so then whether we got the answer...
The counter on the right side also seems to expire faster...good for people who read right to left, not so for people who read left to right (as English does). Wasn't really an issue until about the 8th or 9th one, or there abouts...