How can you put thousands of instance_ids into a mass update batch?

My user is trying to do a mass update of several thousand installed base instances. 

1.  He creates a new batch.

2.  On the screen where you select your instances, he queries by account number, and 600 instances are displayed.  He clicks 'select all', and "apply" to add them to his batch. 

3.  So far, we have 600 records in our batch.  We would expect another screen which would show us the next 600 records belonging to this account number, but instead, we see this screen. 

What is the purpose of this screen?  I cannot find it in the User's Guide.  I was hoping these would be additional instances we could add to our batch, but when I click "select All" and then 'Add', the screen reverts back to the original screen showing me the 600 instances.