I am working on a nav which includes a page that has a single sub page like so: Home > Careers > Profile. If I want people to go to the overview or landing page first which has the majority of the information on it, would having a single drop-down item be misleading to people and deter them from clicking on the main nav item? Should I create a second drop-down item to link to the parent page?
Based on my experience and watching usability sessions I found that having a link behind a parent is not a very good practice.
A good number of people "click" to open menus instead of assuming / knowing that it works on mouse hover (desktop).
On mobile devices there is no "hover", and "hover" event translates to "click". This can cause issues if your menu item has a linking to a page and also has a "hover" event to open a second drop down.
Given the reasons above, the best approach in my opinion is to have parent items "unlinked" and have two drop-down items instead. Ex:
Home > Careers > Profile > Overview
Home > Careers > Profile > Form Page
NOTE: I also do agree with comment left by Simon, you should cross link both "Overview" and "Form Page" allowing users to quickly navigate between these pages instead of forcing them to use the multi-level drop down navigation.
P.S. If you only have a single page then you should not need a second drop down.
You could combine or split the navigations.
Either separate them out into two different navigation items at the top level or combine both items under some other top level menu on your site.
Its also OK to have a link to the parent page as long as all sets of parents with their children follow the same pattern, so if you decide to link to the parent as well as the child in one menu structure then make sure than all structure behave in the same way.
If I was to deduce from your example that 'profile' is some sort of personal account page, you could consider removing that from the menu altogether and giving it prominence like a login / account page then lead people to sign up via the careers page.
Unless you are being ultra clear that the second link in the drop down is another link to the same page, I'd steer away from duplicating nav links. For the people that do get the structure, it may be confusing as to why you have two links to the same page. One that spawns the drop-down, and the other inside the dropdown...
Also, I'm assuming you will have more than 1 top level link that spawns a drop down? These other dropdowns by the sounds of it have more content than just 1 page, which would give a clue as to how your page is structured and interacted with.
I'm also assuming your drop down is spawned on mouse hover? Could you give another visual indicator that the "Career" link is also clickable? Perhaps test underlining the link. Something else to bear in mind with this approach is, unless you have specific mobile ideas and designs for your IA, the on hover drop down solution will need to be re-treated.