Will Microsoft Project 2010 allow you to sequence (link)summary tasks? Yes! Whether you should is the question.
When including summary tasks in a project’s dependency chain, be careful! You might miss out on opportunities to shorten the project schedule.
In the figure below I have created two summary levels of activities and turned on the Project Summary task. This format will ensure that project duration changes are observable. Please note that the project duration is 6 days and is Auto Scheduled for the purposes of explanation.
The next two figures illustrate how efficiencies may be lost when summary tasks have dependencies. In the next figure, the two summary tasks are linked. This tells Project that all of the sub-tasks in the second summary task must follow those of the first summary’s sub-tasks. Note that the project duration is now extended to 12 days.
If the tasks under one summary do not have links to tasks under another, all is well. (This is often the case in SCRUM and other Agile scheduling techniques.)
If the sub-tasks do have dependencies under other summary tasks, the summary links can create a schedule issue. Look carefully at the figure below and note that I made sub-task 2 a predecessor of sub-task 4. The schedule was not shortened due to the summary task links! The duration of the project is still 12 days, and none of the start or finish dates have changed.
When the links are removed between the summary tasks, Project can optimize the schedule. In the figure below, note the overlap in schedule between summary levels and also note the change in the project duration to 10 days.
Don’t let yourself get caught in summary task scheduling issues. Until you are very familiar with MS Project’s scheduling engine, leave summary tasks out of sequencing.
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