How to stop playing games with your project schedule.
Most recently baselined project plans are inaccurate because they have unrealistic start dates, finish dates, work hours, costs and/or durations. Poor estimating during the planning phase is a big contributor to project failures.
However, project managers can build more accuracy and credibility into their project plans by incorporating the 20-percent solution into three areas.
No one is available to work on projects 100 percent of his or her time—people take breaks, attend meetings, get stuck in traffic and so on. Therefore, you should make the assumption a resource is unavailable 20 percent of the time and available 80 percent. ...