Never mind, I found an even better way; having it update once per frame if you created or destroyed at least one building during the previous frame.
Also the Cosmic Gear is now an all-around negative space wedgie. In addition to speeding up or stopping the calendar, it now emits a chrono-backlash that has an effect on nearby creatures, and two Gears in close proximity with reversed polarity can create a 'chronal torque' effect. It can be used as an time-loop based shield, time cloning device, teleporter, extraspatial creature storage mechanism, or aging-based weapon. It can also de-age creatures until they will never have been born, which will bring creatures that they therefore couldn't have killed back to life as well as erase all of their descendants from existence. I have no idea how exploitable this system is. Since you can, with sufficient precision and effort, age and de-age creatures, you can create paradox-based gambits ... although if you abuse it, you might eventually find yourself besieged by long-dead enemies. And versions of them that fell out of parallel universes. No actual clock roaches currently but I think it may be fun enough as it is.