Is a feature landing page necessary when there’s only one feature?

We have a web portal with a main menu and submenu. The items in the submenu link to an overview page of more articles.

There are 6 submenu items. 5 link to an overview page which let the user choose an article and then go directly to the detail page. 1 of them links to a calculation tool. Right now there is only 1 tool but there will be more in the future (1-2 years), so the 1 link directly goes to the detail page with the calculation tool.

Some of my colleagues think this is not logical. They say that, since the previous 5 submenu items navigate to an overview page first, the 1 link should also go to an overview page (and also show the one item) before the user can go to the detail page.

Flow of what I designed:

submenu item 1 - overview page of articles - detail page  
submenu item 2 - overview page of articles - detail page  
submenu item 3 - overview page of articles - detail page  
submenu item 4 - overview page of articles - detail page  
submenu item 5 - overview page of articles - detail page  
submenu item 6 - calculation tool (detail page)

Flow of what they suggest:

submenu item 1 - overview page of articles - detail page  
submenu item 2 - overview page of articles - detail page  
submenu item 3 - overview page of articles - detail page  
submenu item 4 - overview page of articles - detail page  
submenu item 5 - overview page of articles - detail page  
submenu item 6 - overview page of the one calculation tool - calculation tool (detail page)

Is it really necessary to direct the user to an overview page—showing a single item—for the sake of consistency?