Why would you. The data is there to demonstrate what impact faster RAM has on a system. The test would be far less valid if each run was tweaked for fastest RAM performance. Especially if those tweaks are not universally achievable.
The tests demonstrate clearly what faster RAM -can- do for you. There is little benefit it excessive granularity here.
The tests demonstrate the impact of faster RAM with lower latencies. And the test is completly unfair to lower speed chips if it keeps the timing at CL9, as even the cheapest DDR3 1066MHz RAM has CL7 (and DDR2 800MHz has CL5, havent seen any DDR3@800MHz). Why is it more relevant how a crippled CL9@1066MHz would perform than a real one?