I've taken 8, and I plan to take 5 more before the test day. My prep course instructor, as well as my pre-law advisor, both agreed that it is not good to take tests daily. On the off days I am going through and reviewing a question type each day. EX: Monday-LR Flaw, Tuesday-Games Matching, Wednesday RC Main Point, Thurs Exam, etc.
The final week I will be taking an exam every other days and reviewing all question types on the off days.
I guess it's different for every person, but I have found that taking at least 5 timed tests a week has really helped my mental stamina, concentration and confidence. I used to really dread taking a full-length 4-5 section LSAT in one sitting and was always counting down how many more questions I had left, etc., but now, it's become almost second nature.
It may sound crazy, but I'm trying to train myself to perform under any circumstances come test day, which means taking these tests even if (and especially when) I'm tired, sleepy, hungry, bored or just unwilling to sit through the test. I don't want to do well in practice only to bomb on test day because I didn't get enough sleep, was stressed out or felt sick...although I will take a few days of rest in the week before the test.