The Organizing Principle
The question is not how many projects you can have -- you can have as many as you want. The question is how many you actually need. The answer: one per distinct context where the relevant background information differs significantly.
If you run one business and most Claude conversations are about that business, one project serves you. If you run multiple brands with completely different audiences and voices, each needs its own project.
The trap to avoid: creating too many projects and not maintaining any of them. Two well-maintained projects are more useful than ten outdated ones. Projects only work when documents are current.
Common Project Structures
Single business owner: One project for the business with Business Context Document, Brand Voice Guide, AEO Strategy, and Concept Framework.
Multiple brands: One project per brand, each with its own complete set of context documents. Claude never mixes brands.
Professional plus personal: One project for professional work with professional standards and vocabulary. One project for personal creative or business work with a different voice and context.
Client work: A separate project per major client if the work is substantial enough to warrant it.
Maintenance Is the Real Constraint
Each project requires regular maintenance -- particularly the current priorities section. Before adding a new project, ask whether you will maintain it. A neglected project runs but advises based on outdated information.