Forum Discussion
What is a best practice for linking Just-In-Time Tasks?
In MS Project, what is a best practice for linking Just-In-Time tasks, so that a task is scheduled to take place just prior to another task, without use of date constraints or overriding scheduling logic?
As an example, I have a task "task prep" that I want to complete just before "important task" starts. "Important task" has other Finish-Start predecessors that determine when it starts. The only thing driving "task prep" is that it must finish just before "important task" starts. These tasks have slack in the schedule that I want to maintain, so I can't use As Late As Possible constraint without pushing both tasks to the right and using up slack.
There isn't a task preventing "task prep" from starting, so if I link "task prep" as a predecessor to "important task" with Finish-Start (FS), with As Soon As Possible, then "task prep" will be scheduled to happen long before I want to perform that task.
If I use Start-Finish (SF), then the start date of "Important task" drives the finish date of "Task Prep" The dates line up, but SF dependency type is generally not recommended. Also, I do not want to use date constraints, as these are generally not recommended.
How can I link these tasks so that "task prep" finishes just before "important task" while adhering to accepted scheduling standards?
3 Replies
Yes, absolutely. Years ago I did a couple of training classes for two groups of project managers at NASA. When we talked about the SF dependency, they described how the launch of a rocket is a "sacred event", whose date and time are "etchec in store" so to speak. They have a final milestone in their projects that represents the date and time of the launch. Then the final sequence of activities that must be performed before the launch are all linked from the launch milestone backwards using the SF dependency. So, your use of SF is reasonable, given the situation you describe. As an aside, when I finished my classes with the NASA project managers, I asked them how I could volunteer for the first manned mission to Mars. And they all laughed at me! This was LONG before Elon Musk and SpaceX, by the way. HA!
I understand your hesitation in not wanting to use a Start-to-Finish (SF) dependency, because it means you are scheduling backwards. In fact, several of my clients PROHIBIT using an SF dependency. However, I am a Baby Boomer, which means I believe "Rules are meant to be broken." In your situation, the SF dependency is the only dependency that actually models the scheduling behavior your are seeking. Therefore, I would recommend you use the SF dependency in your situation. Hope this helps.
Thank you for the quick response! I have a similar question about SF relationships. In reviewing a schedule, there is a chain of 8 or so tasks, all linked with SF relationship. The reason given is similar to above, that the last task in the chain is important and should drive when the prededing tasks are done. Would the SF dependency still be recommended in that situation?
Thank you
