In the field of second language acquisition, there is a theory that has been developed by the very popular academic Stephen Krashen. His theory is that skill in a language is generally determined by the amount of comprehensible input taken in by a student. For instance, somebody who has successfully read and understood ten novels in a particular language will likely have a much greater grasp of it than a person who has read one.
From my prior experience, this seems to be generally true. As somebody who had spent, prior to this test, a few years studying Latin it seemed as if it improved when I read a lot more text. One of the things that I noticed while studying Latin was that one of the easier texts for beginners to study was the Vulgate Bible.