changing state of an object ona different slide

Yes, that makes sense.

The basic programming works the same whether the user returns to the menu slide after visiting each section/slide, or whether they step through the sections/slides using the Next button. 

In your project, you can still use variables to track that the user has visited slides 1.6 - 1.10.

• Each slide could have a trigger that adjusts its corresponding variable to True. That could be done when the timeline starts, or when they finish any interaction on the slide.
• If they use the Next button to visit each of those slides, all the variables will be True when they return to 1.5.

And the triggers on 1.5 could change the states of the objects when the timeline starts based on the value of the variables.