When to use nested tasks?
 

I only recently discovered that OmniFocus for iPhone supports sequential and parallel nested tasks. This is academically interesting but I haven't really found a use for nested tasks. That is, my projects consist of a list of tasks 1...N, but I've never really had the need to subdivide a task within a project into smaller (sequential or parallel) tasks. I've tried, but I find that so much nesting leads to complexity without really solving any problems, so I tend to flatten projects into simple lists.

Of course I realize that my lack of need for nested tasks is likely just a product of the kinds of projects I work on, which (apparently) serialize well without needing the additional level of hierarchy.

However, nesting tasks is a cool feature. Are there any other interesting/useful/unconventional uses for nested tasks other than the obvious?

If you start doing something you expect to accomplish in one sitting, but are interrupted, you can add a nested task to it to show you where to resume. An advantage of doing this over simply modifying the original task is that you've still got the original task there when you look back at the project later.

Another common way the nesting of tasks is useful is preparing for some activity. A parallel group of tasks up front to collect signatures or feedback or parts or tools, followed by a sequential block of tasks to do the work. The parallel group allows all those tasks to be active when you encounter the colleagues or merchants, whereas doing it with a completely sequential project means you're likely to do it inefficiently if you didn't guess the optimal order.

That's a very good idea. It's like being able to annotate except better than a note because I can add more than one sub-task with a due date, context, etc. without modifying the original task, as you pointed out.

The second use case you described sounds like using nested tasks like embedded checklists. Also very cool.

Thanks for taking the time to reply!