Hi Alyssa. Tribe does not send a notification for every single post generated in the community. This is not the best practice and will be overwhelming for the users to receive any notifications about the subjects that they do not have interest in.
The way Tribe handles the notification is based on the user's interest. For example, if a user follows a topic page or joins a group, if there is a new post under that topic page or a group page, the user can receive a notification. Or, if user A is following user B in the community, as soon as that user B shared something in the community, all his followers, including user A, will receive a notification.
In this answer,22 you can learn more about why/when Tribe generates a notification for a user.