Deciding how often to clean the inside of windows depends on various factors such as your location, the location of the window, environmental conditions, and of course, personal preference. Generally, it is recommended to clean the inside of windows at least twice a year. However, if you live in an area with high pollution or dust, more frequent cleaning may be necessary. Additionally, if you notice smudges, streaks, or buildup on the glass, you may want to clean them more frequently. Some individuals prefer to clean their windows on a monthly or quarterly basis to maintain a consistently clean and clear view. Ultimately, the decision on how often to clean the inside of windows is subjective and should be based on the specific needs and preferences of the individual.