The document database model in MongoDB requires proper data modeling to take into account constraints such as network and hard disc speed, maximum file size of documents, and features that may be added later. The optimal grouping of objects into collections is determined by the workload, and a three-phase process involving the workload, relationships, and optimization patterns can help determine the best data modeling approach. Data access patterns, such as storing related data together, are crucial in MongoDB, which allows for efficient read-write performance when properly designed schemas are used. Techniques like referencing and embedding can be employed to model complex data relationships, while a well-designed schema can reduce computation, I/O, and contention, making it easier to filter and retrieve data with minimal overhead.