I'm playing with OmniPlan b10, building out a project plan for a system deployment. The first stages of my plan include two tasks each with a series of subtasks. Many of the subtasks are dependant on one another, but not all. In my case, I have Task 1.1 as "Deliver 7 x 500 GB Drive Modules" and Task 1.5 as "Install 7 x 500 GB Drive Modules"; Task 1.5 depends on the completion of Task 1.1, so I construct a finish-start connection between them. When I do this, OmniPlan automatically reschedules Task 1.5 with a start time immediately following the end time of Task 1.1, even though I have scheduled several additional subtasks in the intervening time period.

Something similar happens across subtasks of different "higher level" tasks. I have Task 2.5 (disconnect the Xserve G4 from the RAID) dependant on Task 1.3 (take Xserve G4 offline). However, these two events do not need to happen one right after the other. Task 1.3 only has to be complete by the time 2.5 starts, which is my understanding of a Finish-Start connection.

My question is why is it reasonable for OmniPlan to always reschedule a task in such a way? I don't need to start the subsequent task immediately upon completion of the previous task, but OmniPlan seems to want me to, even if I have a different order of operations in mind.

With the understanding that i'm very new to OmniPlan and Project Management, is there a critical PM concept that I'm missing?

[skwirl]

When using a Finish - Start connection, it changes your task's schedule to "As early as constraints allow". With that setting, it places the task to the earliest start time possible, which is right after the task most of the time. You can always move the task after the connection is made to your desired start date while keeping the connection. Doing so will change your task's schedule to "On Specified Date".

On the other hand, I see your point. If the task is already starting when you want it to why should OmniPlan move it, forcing you to move it back right after making a Finish - Start connection?

I'll file a bug report in our database about this to see what the other engineers think. In the mean time, you could lock the start dates of your tasks by clicking the lock icon in the "Task : Information" inspector. You can also do this by holding the "Apple" key down and clicking on the starting end of a Gantt bar. This should stop the task from moving when you create a dependency connection. Keep in mind though, doing this will mess with the leveling feature because OmniPlan won't be able to move the tasks around since they are locked down.