Mongodb design pattern for large applications

I'm working on a large application with multiple products (micro-services), user management, and aggregation of meta data.

I've laid out my mongodb with multiple databases/collections as follows:

DB: product 1  --> Collection: product 1 data 
DB: product 2  --> Collection: product 2 data 
DB: product 2  --> Collection: product 3A data,   product 3B data
DB: usermanagemnt  --> Collection: user data,   client data
DB: aggregate  --> Collection: Client aggregates,   User aggregates

Are there known design patterns for Mongo when establishing a setup like this, to me this seems like the most logical approach but I've seen other projects with 1 db, and a multiple collections.

Just looking to hear from others that have built larger applications and how then went about designing the MongoDB layout. Links to any best practices, etc. everything I've stumbled across on SO and online generally deals with much simpler applications.

Are there any drawback with the approach I'm taking above?