The short answer is: Yes, you probably should.
True, there are some disadvantages. First, it's administered in the dead of winter and it's nondisclosed, meaning the test content is not made available after the fact. But consider this: the January test may be your best—and last—chance to get the score you need and still apply for admission in the fall of 2019. Virtually every law school will accept scores from this test as you'll see in our survey of the top 100 law school LSAT deadlines.
And if you're planning to start in the fall of 2020? You'll be well ahead of the game and can have your applications ready for submission as soon as schools begin accepting them next fall. You'll also have plenty of time for a retake if you need, or feel you can attain, a few more points!
Admittedly, this may sound like somewhat self-serving advice: we'd certainly love to have you work with us, whether you take one of our Winter Full Length or Live Online LSAT classes (starting mid-December!), sign up for a tutoring package, or spend a few months using our On Demand LSAT Course. Nevertheless, even if you don't spend another dime on prep, you should consider the January test to be a viable retake option if you believe there is any room for improvement.
So let's look a little more closely at why the January test is worth considering: