Levelord: Always a tough question. Levels start on paper, both as gameplay and key-moment descriptions, as well as top-down and special event diagrams.
Then the level designer will cast the basic geometry and lighting. This is followed by the first pass at character, weapon, and placement of other basic essentials. Then the level is combed and combed with many passes as it approaches its finish. Finally comes all the playtesting and tweaking.With multiple levels being designed during the game's development, it is hard to single out the time allotted to an individual map. A good average, though, for CS:CZ would be 12 hours a day, 6 days a week, for 8 weeks...about 600 hours per level.