I've asked this question around before, and the answer is pretty much the same replies....still, I'm not sure. Here's why.
If I take 2 a day, won't it be like mental bootcamp, and when I get to the real thing--one measly test in the middle of the day--won't I completely kill it??
I know I'm not crazy.
Don't know if you're crazy or not, but I can tell you that taking two LSATs a day for the week prior to the exam IS a crazy idea. IMO, what you're going to end up doing is burning your brain out. Sure, taking just ONE test after days of taking two back-to-back will feel easier; but I'm thinking that you won't be operating at peak levels. It would be like saying that running 50 miles every day for the week prior to running a marathon is a good idea, because then running the 26.2 miles on race day will feel like a piece of cake. Sure, it might feel shorter, but you'll be so sore and tired you probably won't finish the race (and, if you do, you won't end up with very good time--and maybe you'll have to crawl some of the way to the finish line).

Avoiding burnout is important. Taking two timed practice tests in a day is the perfect formula for burnout (AKA it is a sufficient condition).
You also have to be careful with the 'one a day' plan leading right up to test day. Your brain and body need decompression rest and relaxation time in the final week leading up to the real thing so that you will be functioning at your peak potential when it counts.
It's good to take the day before the test off from timed practice and intense studying, especially since the LSAT is not a test you can significantly improve performance on by cramming last minute.