meteor puzzle

I noticed that SBCL does not have an entry for the Alioth Shootout
Meteor Puzzle:
http://shootout.alioth.debian.org/gp4/benchmark.php?test=meteor&lang=all


So, being 1/2-way through PCL, now is the time to start thinking about
contributing it.

The spec of the problem and a series of solutions is given here:
http://www-128.ibm.com/developerworks/java/library/j-javaopt/

But I will start with my first question about their listed solution.
Why is each piece used exactly 5 times? Is an acceptable solution to
this puzzle to use one piece 6 times and another 4? I saw nothing in
the problem description precluding this. In fact, I dont even see a
problem description. They just start offering solutions.

.