When an education or training website starts with a handful of articles, putting them into a few broad categories feels straightforward. The trouble usually shows up later, once the library has grown enough that a single category page lists dozens of entries and visitors can no longer scan it quickly. At that point the category structure itself becomes a usability problem rather than just an organizational one, and the fix often requires rethinking how topics are grouped rather than simply splitting one folder into two.
One practical starting point is to look at how your categories are named. Names that made sense when the site was small can become ambiguous as content accumulates. A category called "Basics" might have covered introductory material for one subject early on, but after two years it could contain beginner content for several different subjects, making it hard for a returning learner to predict what they will find. Reviewing category names against what actually sits inside them, and renaming or splitting where the label no longer matches the contents, is a low-cost step you can do before attempting any larger restructuring.
Another approach that helps as volume increases is separating categories from tags. Categories can remain a small, stable set of high-level groupings that reflect the main subject areas your site covers, while tags handle the cross-cutting dimensions such as difficulty level, format, or prerequisite knowledge. This keeps the primary navigation shallow enough to browse without forcing every article into a single rigid slot. You can try this by picking a handful of your most visited articles and checking whether a single category placement actually describes them well, or whether a second dimension like "beginner" or "video-based" would help a visitor filter more usefully.
It is also worth setting a rough threshold for when a category has grown too large to remain useful as a single page. Some site owners find that once a category listing exceeds thirty or forty items, visitors stop scrolling and start using search instead, which suggests the category is no longer doing its job as a browsing aid. You do not need a universal rule here; checking your own analytics for how far down category pages people scroll, or simply asking a few regular users to find a specific article by browsing alone, can show you where the structure is breaking down. The key is to treat category design as something you revisit periodically as content grows, rather than a one-time decision made at launch.