Every car is going to be different. Just because oyu have a 180* thermostat doesn't mean the engine temp will be at 180 degrees.
For example, with my car and a 180 stat, the coldest the engine will run is 188 degrees. Usually, when on the highway, or a 45MPH secondary road, airflow across the radiator is all that is needed to maintain that. If i idle, the temp creeps up.
My fan comes on at 210 degrees, and shuts off at 195 degrees. With that range, it really only comes on at stop lights and idling in traffic. When crusing around my temp hovers around 188-190 degrees and the fan is off. Having the fan on here won't drop temp any further.