The frequency with which a piano needs to be tuned can vary depending on several factors, including the piano's quality, its age, the environment in which it is kept, and the amount of use it receives. In general, it is recommended to have a piano tuned at least once or twice a year for most situations.

However, there are some exceptions. New pianos, for example, often require more frequent tuning during their first year since the strings and other components need time to settle. In some cases, it may be necessary to tune a new piano four times in the first year.

Additionally, environmental factors can affect the piano's tuning stability. Fluctuations in humidity and temperature can cause the wooden components of the piano to expand or contract, leading to changes in the tension of the strings. Pianos located in environments with significant humidity or temperature variations may require more frequent tuning to compensate for these changes.

If a piano is heavily used, such as in a professional setting, it may require more frequent tuning. Concert pianos, for instance, are typically tuned before each performance.

Ultimately, it is best to consult with a professional piano technician who can assess your specific piano and its needs. They will be able to provide guidance on the ideal tuning schedule based on your circumstances.