They exist only to deal with personnel bozos, bean counters, senior planners, and other mental midgets. Real Programmers scorn floating point arithmetic. The decimal point was invented for pansy bedwetters who are unable to think big. Real Programmers don't believe in schedules. Planners make up schedules.
Managers firm up schedules.
Frightened coders strive to meet schedules. Real Programmers ignore schedules. Real Programmers don't bring brown-bag lunches. If the vending machine sells it, they eat it. If the vending machine doesn't sell it, they don't eat it.