I think you may mean Accordion rather than Card-based.
TL;DR: Ditch the accordion, show them the topics as headings, and have the sub-sub-topics and questions on a separate page.
Alan Cooper recommends to avoid hierarchies greater than one level deep where expanding navigation is concerned:
Most humans are familiar with hierarchies in their business and family relationships, but hierarchies are not natural concepts for most people when it comes retrieving arbitrary information
Developers are comfortable with nested systems, in which an instance of an object is stored in another instance of the same object. Most other humans have a difficult time with this idea.
"Accordions increase interaction cost"
Nielsen notes that forcing users to continually click headings to access their content can be cumbersome, annoying, and adds to cognitive load:
- Forcing people to click on headings one at a time to display full content can be cumbersome.
- Especially if there are many topics on the list that individuals care about. If people need to open the majority of subtopics to have their questions answered or to get the full story then an accordion is not the way to go. In this situation, it’s better to expose all the content at once.
- Accordions increase interaction cost.
- Readers treat clicks like currency: they don’t mind spending it if the click is worthwhile and has value. However, resentment ensues when a click is considered a wasted effort; it doesn’t take many wasted clicks to escalate people’s reaction to full-blown defiance.
- Hiding content behind navigation diminishes people’s awareness of it.
- An extra step is required to see the information. Headings and titles must be descriptive and enticing enough to motivate people to “spend” clicks on them. When content is hidden, people might ignore information.
Ditch the accordion and simply show them the topics as headings.
A simple hierarchy like this:
- Major Topic 1
- Major Topic 2
Clicking a sub-topic brings you to the page containing the sub-sub topics as headings, with the questions underneath each heading.