Further experiments.
In another experiment with a larger reactor I played with the rod percentages. it was a 9x9x6. It started out at 1622 temp, 20.4k RF, and 0.312 fuel. Raising all thirteen rods to 60%, except one at 50%, I got it to 1000 temp, 12.4k RF, and 0.13 fuel. A 40% reduction...