Size of Bounded Contexts
How many Modules (9), Aggregates (10), Events (8), and Services (7)—the primary building blocks of a domain model created using DDD—should a Bounded Context contain? That’s a bit like asking, “How long is a piece of string?” A Bounded Context should be as big as it needs to be in order to fully express its complete Ubiquitous Language.
Extraneous concepts that are not truly part of the Core Domain should be factored out. If a concept is not in your Ubiquitous Language, it should not be introduced in your model in the first place. Still, if one or more extraneous concepts creep in, get rid of them. They probably belong in a separate Supporting or Generic Subdomain, or in no model at all.
Be careful not to mistakenly factor ...