When considering ice screws and other winter climbing protection, it should be emphasised that by far the best ice climbing protection gear is rock climbing protection gear. If you can place wires, nuts or slings, then do - they will be far stronger and quicker to place than most ice gear. And despite the general preconception that cams are useless in winter, they are actual well worth carrying as long as they are not placed in icy cracks.
If no rock gear is available then Ice Screws (in good ice) and pegs are the next best options, and only as an absolute last resort, Warthogs, Deadmen, Snow Stakes and Hooks.
Having said that many hard ice routes such as Orion Direct (V) on Ben Nevis require a rack of at least six screws minimum, two for a belay, two or more for runners and two for the next belay.
Ice Hooks are probably the least reliable ice protection short of a tied off sock, but they do have their uses and those uses are: quick hook placement in hollow ice, shallow turf ledges and ice smears too thin for a screw. They are also great for whacking into iced up cracks, particularly corner ones where you would be pressed to place a peg. Of these placements, their most unique use is in turf, particularly the well frozen rim of exposed turf often encountered on mixed routes, where they can provide crucial psychological (if not actual) protection for the next move. Hooks can also be used for frozen turf belays at the top of crags, but a fully driven in Warthog is more reassuring. Warthogs are also useful for running belays and belays where the turf is thick and well frozen.
For really marginal turf placements on harder routes and for shallow iced up cracks, we have been selling a remarkable number of Peckers recently!
Belaying on steep snow where ice screws are useless and there are no rock outcrops is one of the more worrying aspects of mountaineering. All mountaineers should know how to construct a buried axe belay and a snow bollard. The advantage of these is that they do not require anything extra to be carried - the disadvantage is that they are fairly time consuming. Deadmen and Snow Stakes are quicker to use, and the former can be very effective if placed correctly.