[Stephen Brown]

In the GTD book, David Allen defines a project as any outcome that requires more than one standalone task to complete. Using this as a basis, I set up my projects as;

Example of a sequential project where each task must be completed in order:
Order print job A from company X
1. Email Company X for quote
2. Place purchase order with Accounts Payable
3. Email Company X purchase order
4. Receive and check print job A
5. Receipt print job A on system

Example of a parallel project where tasks can be completed in any order:
Income Reconciliation 2012
1. Compare actual income against projected income for last month (recurring)
2. Ensure all invoices raised last month are accurate (recurring)
3. Check aged debt reports and refer to collection agencies (recurring)

Technically, the parallel project is a single action list but, as the tasks are all related to the same outcome, it is a project.

As a last resort, I would only use a single action list for miscellaneous individual tasks that are not related, for example;

Single action list: Miscellaneous
1. Process internal post (recurring)
2. Return Jim's call regarding his IT issues
3. Sign up to knowledge hub at website A
3. Pay money for lottery syndicate (recurring)

Hope this helps.