Why Does Velocity Only Explain PrepTests 29 and Newer?
We want to give you plenty of practice explanations, and we want to prepare you for the test as it is today, and we don't think it makes much sense for you to pay for a bunch of old tests that (A) you may not need, and (B) may not accurately reflect the LSAT as it's administered now.
How did we decide specifically to use tests only from this millennium? Mostly based on the Games sections, really.
Our earliest test explanation is for PrepTest 29—the October 1999 test. In the tests in all the years since then, only very few games have not been readily susceptible to one of the five major templates that Dave outlines in our course. However, if you go back even a couple of tests earlier, you begin seeing more and more "weird" games. Go back past PrepTest 20, and you start to see lots of whole sections popluated by games that are very different from those on recent tests.
This phenomenon - the evolving test - isn't limited to the Games section.
We think you'll find that in the Logical Reasoning sections of the test, the older material contains a higher percentage of "weird" questions: questions that don't conform - either in their apparent demands or in their accepted answers - to the expectations set by today's tests. If you take these tests alongside some newer tests, we think you may find these older LR sections - like their older Games cousins - more difficult than current tests (largely because of the decreasing conformity to patterns that are strongly held on today's tests).
Finally, the Reading Comprehension sections of older tests often seem easier, on the whole, than do today's sections. On old tests, the RC answer choices seem more distinct from each other, and the wrong answers are wrong for what seem to be more obvious reasons.
Now, we don't mean to imply by any of this that all material older than PrepTest 29 is crap. We don't think you can draw a bright line like that. However, we do feel that basically all material since 2000 is very indicative of the test as it appears on modern administrations, and that material older than that often differs - sometimes significantly.
So, while a person can make good use of older material (just please keep in mind the potential for difference, as outlined above), we don't think it usually makes good sense—or smart prep—to spend time and/or cash on material that may not be the best possible use.