This is one of those bits of oversimplified, or out'n'out
mis-information, that we run across all the time in this industry.
Because the law schools average, there's a strong incentive
not to take the exam more than once. But since the LSAT score is
the single most important criterion for admissions, you MUST take
the exam a second time -- and score your best, or closer to it --
if you've already put a bad score on record.
The best thing you can do if you already have a less-than-best
score on record is to ensure that your higher score is higher by
AT LEAST 8 POINTS, if at all possible.
That's because the margin for error in the exam itself is
about +/- 3.5 points -- meaning that a jump of 7 points could be
written off to the measurement error of the exam. (You go from 155
to 162, you've arguably got a 158.5 +/- 3.5.) But an increase
of 8 points or more can NOT as easily be put down to measurement
error -- and you can make the case to the schools that (for whatever
reason) they should consider your higher score more "predictive"
or representative -- and that they should not hold your previous
failure to recognize a bad day in time, and to cancel your performance,