Navigation solution.

As Greg points out, you need to create a user variable for each slide for which you want to use this functionality.  It will be a Boolean, has a default value of 0 and will get a value of 1 when leaving the slide. You didn't tell how you set up the normal navigation? If you use a custom Next button, one instance on each slide, you could use that button to Assign 1 to the variable before leaving the slide. The On Enter action can then be used as described by Greg. 

I you do not have a Next button, you can combine the toggling of the variable with the check of visit.

IF var is equal to 1

    Jump to slide

ELSE

    Assign var with 1

    Go to Next slide

There may be another way but here is one idea.

What if you made a variable such as

slide5viewed

Then have an onEnter action for slide 5 to increment that to a 1

Then - on your button that goes to slide 5 - place an advanced action that checks that variable

Basically -

if slide5viewed = 1    jump to a different slide

else go to slide 5