You should detail your car as soon as it needs to be done. Drivers may need to pay more attention if you're in an area of the country with harsher elements - especially when winter is coming.
If not properly maintained, the car body will become damaged and unhealthy much faster than normal.
It's important to remember that regular detailing is necessary on any type of vehicle because they provide protection from environmental hazards like UV rays or acid rain which can eat away at even the most durable finishes over time.
So all things considered this would typically mean that detailing should be carried out every six months for daily drivers