In his book about Kanban, David J. Anderson shows us how we can handle activities that are not actually having a specific sequence. Some activities can be executed in any order as long as everything is done before proceeding with the next step in the process. This is especially true for creative activities.
Unordered Activites on a Kanban Board
For me good examples for this type of “sub-tasks” are activities before publishing something in marketing or the Definition of Done in software development.
Pattern #1 – The Single Column
Only use one column for the process step and put the sub-tasks on a checklist. Check every sub-tasks when it is completed. As soon as all checkboxes are checked the card is ready to move on to the next status (column) in the process.
Pattern #2 – The Horizontal Split
Use the same checkbox like in pattern #1 but additionally split the column horizontally. Now move the card through the horizontal lanes. This makes if very transparent where there is free capacity, if the horizontal lanes belong to specific team members.
Source: Kanban: Successful Evolutionary Change for Your Technology Business by David J. Anderson, Mapping the Value-Stream (Chapter 6)