Well, I did a test last night. I had one planet that had 2 Rebel Heavy Weapons factories and one planet that had 5. I started the production of a tank at the same time on each planet. The planet that had 5 produced the tank significantly faster. So, in a war of attrition having a planet with 5 or more factories would be a big boost. Ok, next question. Would having more than one Ion cannon increase the recharge time during space battles?