This is just a thought.
One thing I would love to see in future study materials is animation. A long time ago, I remember a company (CBT?) that did this type of training. Everything had animation. But did not have voice-over, like an INE instructor talking.
One good place for animation would be QOS along with ingress/egress queues. This is one area that still illudes me a little.
With all of the new software programs and the people with the graphic/animation skillset today, it might be a lot cheaper than it was 10+ years. Just a guess. I do not have any idea how much something like this costs to have done.