The JSON flexible schema data model is well suited for the ambiguous nature of the activity object, allowing for multiple variations in structure to accommodate different CRM needs. The use of Couchbase N1QL as a query language provides a SQL++ implementation that can efficiently satisfy complex data visibility rules, such as direct and team access, hierarchical access, and custom business rule access. This approach enables the effective management of activities in a CRM application, addressing challenges related to volume, data access, and slow system responses due to complex queries. By leveraging N1QL's query construct, which is similar to SQL but simpler, developers can create robust and efficient data models that meet the functional requirements for direct and team data visibility.