Prepping for the LSAT shouldn’t be nearly as time-consuming as most people make it out to be.
If you really pay attention to the bizarre design of the test, you can make significant progress in as little as a day or a weekend, believe it or not. Getting to the point where you’re routinely in the 170+ range can take longer, but not because you have to learn a whole bunch of stuff; it’s more that the LSAT just shows you the same things over and over again, and to score higher than 170 you have to make very few mistakes on the test. Because mistakes are very easy to make on the LSAT if you don’t read it carefully enough, this kind of flawless execution will take significant practice for most test-takers (but not all).
Some people start prepping for the LSAT literally years before they plan to take it, almost from the beginning of college. (I haven’t met anybody yet who started prepping for it in high school, but I wouldn’t be surprised if there are people out there who’ve done that.) It almost goes without saying, but anybody who needs two years to prep for the LSAT is doing it wrong.
Most courses take a few months, and that’s certainly a popular way to go. I would argue that spending 4 to 6 months is still ridiculous, but it’s better than spending 2 or 3 years.
Most approaches to prepping for the LSAT take so long because they teach formal logic, but my LSAT course focuses on the design of the test, so that you can basically treat the LSAT like a reading test, which is all it is. This type of approach is noticeably easier for most test-takers once they try it, and therefore it is also noticeably faster.
So the bottom line is it’s possible to spend as little time prepping for the LSAT as a day or two. Or, you can spend a year or two if you feel like it. A more common time frame for a lot of my students is probably somewhere between a week and a month. Basically, the more your approach focuses on formal logic (things like the contrapositive, necessity, sufficiency, et cetera), the longer it takes most people to perfect. The more the approach focuses on the plain text of the LSAT, the less time it tends to take most people.
Of course, it’s also true that having more time is usually better for most people than having less time, no matter which approach you use. In other words, most people prefer taking a slow, measured approach, as opposed to feeling rushed because they waited until the eleventh hour to being prepping.
So the best of both worlds is to prep for the LSAT in a way that focuses on the language and structure of the test, but to start doing that well before your actual test date. That way, you can prep in a casual way and reduce the amount of pressure involved in the process.