The old adage that "the first half takes 90 percent of the time and the second half takes the remaining 90 percent" is all too often true. This is not to say that tracking tasks in this way can't be useful. It can give you a good indication of progress and it can be a valuable feedback mechanism for your team. However, you need to view such progress reports with a critical eye.
A better approach is to divide tasks into smaller steps and to simply report on their completion. If a particular task misses its completion date, it automatically triggers an adjustment to the schedule. There should be no ambiguity or confusion.
Scheduling is a fundamental but neglected part of project management. Schedules are often inaccurate or out of date. In that case, they are not a useful tool for the project manager or the project team. Usually, they, and the client, have their attention fixed on the holy grail of delivery. Too often, the intermediate steps become neglected, jeopardizing delivery. By adhering to simple fundamental principles, and by constructing a schedule that is useful, the project manager can turn a schedule from an annoying burden into a useful tool.