Take a Lead or an Opportunity - customise the form and remove all NAV items from Sales, Service, Marketing and Processes and then publish the forms. The Lead completely removes the headings where no NAV items exists from Sales and Service - but leaves Marketing and Processes as 'just headings'. The Opportunity completely removes the headings where no buttons/nav items exists from Sales, Service and Marketing but leaves Processes as 'just a heading'.
Firstly the logic is not consistent; but more importantly shouldn't the logic be to remove 'All' headings where no Nav items exist? From a User perspective this is not 'clean'.