Nobody browses a pattern library the way its author organized it. Clients open the inserter with a job in their head — “I need a pricing section” — and either your categories answer that sentence or they scroll past everything you built. Categories are the interface to your library, and they deserve the same care as the patterns.
Name the job, not the technique
“Heroes,” “Pricing,” “Testimonials,” “Calls to action,” “Galleries” — these work because they finish the sentence I need a…. “Media & text variations,” “Flex layouts,” and “Misc” do not. If a category name describes how a pattern is built rather than what it is for, rename it.
Keep the list short enough to scan
Five to nine categories is the comfortable range. Below that, categories stop narrowing anything; above it, the list itself needs a search box. A category with one pattern in it is a hint to merge; a category with thirty is a hint to split — usually along audience lines (“Heroes” into “Heroes” and “Page headers”) rather than visual ones.
One pattern, one primary home
Patterns can carry several categories, and cross-listing is fine — but every pattern should have one category where it obviously belongs. If you cannot name a pattern’s primary home, the pattern is probably two patterns.
Collections, the same way
On patternbuilderwp.com a pattern’s categories travel with it, but the unit of organising and installing is the collection: Personal on a free account, and on Pro as many private collections as you like — one per client, one per kind of site, one for the sections you reach for everywhere. Nothing in them is ever public. The same discipline applies: a collection that answers a real sentence — “Client drafts”, “Starter heroes” — is one you will actually open on the next site, and if you are a studio whose collection Twenty Bellows publishes, that coherence is exactly what the directory shows.
Ten minutes of renaming is the cheapest usability upgrade your pattern library will ever get.