Subitems are a really powerful way to contol lists of actions required on tasks. For more complicated tasks we often have distinct groups of actions required and these have different spec’s and it would be great to represent those spec’s in the subitems columns but that’s hard when we only have one list of sub items.
An example of this is for development tasks where we have one list of subitems breaking down the task spec and we have fields about the type of sub-task and the details of the features being requested. Then we would like to have a second list that is used for proofing the task which has columns tuned to testing, asking for required information and having the right feedback options which are not suitable for the first list.
While we understand there are other options like checklists and linking to other boards we find these are not really suitable due to the former lacking the schema control which multiple fields provide and the later is a clunky solution in use making it hard for users having to keep jumping between boards when working on a task.
Allowing multiple groups of subitems would allow for much greater flexability and a smoother user experience.