Since dispatch templates do not have anything for CX users to edit, one would not add slots to dispatch templates.
However, if your dispatch template is a snippet, you may want to add slots to it; otherwise, you may get some surprises on publishing behavior!
The issue comes from how touch parent is implemented in version 6. If a snippet does not have any slots, touch parent action will not continue to the next parent! So if a dispatch snippet is used along the active assembly “chain”, updating a child item (and returning it to public) will not mark some of the parents as modified for the next incremental publish.
For more about touch parent and incremental publish, please refer to the this posting: