When working with longer documents/worksheets it's helpful to have additional options to organize and structure the worksheet. Other applications like wxMaxima and Mathematica allow to create structures like on the following screenshot (done in wxMaxima):
{F8202108}
Command, image, text, etc. cells are added as children of such items. Collapsing for example one chapter will collapse/hide all its children including all calculations done inside of this children items. This allows to focus on a certain parts of the worksheet only hiding everything that is not needed now.
Furthermore, the navigation in the document is supported by "table of contents" widget like in wxMaxima:
{F8202116}
By clicking on the items in this widget the user jumps directly to the corresponding place in the worksheet.
The different items used to structure the document (title, chapter, etc.) have different formatting options (font size, bold, italic, color) - this should be done configurable for the user in the application settings.
Also, Mathematica supports the creation of such elements with and without automatic numbering. If the numbers are not required, the user can user the elements without numbering but still benefiting from the additional organization in the worksheet.