Adding to what PLC stated, "...if it doesn't you're a deadman..."
Flukes or deadmen are great in appropriate conditions, already mentioned, and are best in a soft, homogenous snow often found later in the year like summer, autumn and before the new snows. Winter snow packs are layered with all densities of snow from slush, awsome "styro-foam", to ice so employing a dynamic anchor that, as mentioned, dig under action of load it can deflect off a harder layer. Setting the angle for the cable of the fluke can be tricky. Flukes are however pretty compact.
Pickets are like the PHD cameras. Simple and easy. You can pound them vertically or you can always make a "T-Slot" anchor from it. I really like pickets for our coastal rime.
Get out and play with all these anchors in different applications and snow types until failure. Study why they work, and why they don't. That's the best advice you have had already. Plus you can also sport a cool tag on your forehead from examining the failure of vertical picket placement.
