A common question asked by customers is "How often should a piano be tuned?" Although the textbook answer is "every six months", the better answer may be "it depends". Key factors are temperature, humidity, piano type, usage, and what the person playing likes to hear and is able to discern regarding the tuning.
Temperature and humidity may change often in some homes or auditoriums and are are impacted by seasonal changes. The piano owner along with the tuner/technician can determine the optimal tuning frequency.