These tests, again the high quality ones, are formatted like the real thing so you can get used to the question and answer formats and the time limits so nothing will be a surprise on test day. You’ll know what to expect and you’ll be used to going from different concept to different concept as is often required on the ASVAB. For example, on the math section you may have a problem using one popular math principle followed by another problem that relies on a completely different principle. This is common on a broad test like the ASVAB and preparing your mind to make these leaps can allow you to answer more questions in less time and boost your score.
The various armed forces adopted all of those aspects in 1976. At that point in time, the test was in its written form rather than today’s more common form (computerized test format). The written form covers all of the previously mentioned areas as well, which is why both forms are still available. All-in-all that answers the question concerning the intention of the test.