Is the GET request to an enpoint limited to 100 statements? Is there anyway to bump it up in the query string itself?
The LRS limits the # of statements returned on any particular call as a load limiting mechanism.
You should find something like this at the end of the list of statements, if the result set was limited:
Then you would use that relative URL on the TCAPI to fetch the next "page" of results.
To be sure, if access is needed to massive piles of statements, they should be saved in faster storage closer to the client, or at least the reporting information from them should be stored and updated incrementally. Regularly pulling thousands of statements on demand as part of a user's experience is definitely not recommended.