I_is_smart posted...
Tip for lockpicking, if you push the pin back in before it falls all the way, it'll go back up and fall at the same speed. Learn the timing for the slow speed and you'll be set.
The best explanation I've heard is that there are 3 speeds for the tumblers: fast, medium, and slow. When you push a tumbler up, you can actually keep it up by continuing to push up before it falls back down. But the speed won't reset/change unless the tumbler falls all the way back to the bottom. The speed you want is slow, and apparently lots of people confuse it with medium. Just let the tumbler fall back down until you find something noticeably slower. Once you get a slow tumbler, just keep pushing it up until you're ready to lock it in place. Once I heard that explanation, I finally understood how to do lockpicking even at Very Hard.