How often should the throttle be cleaned? I don't understand this minute.

Whether the throttle is dirty or not is related to your environment. If the local area is dusty, clean it often. You can look at the pipe connecting the air filter at the door of the solar term. I suggest you buy a carburetor cleaner, remove the throttle and clean it yourself. There are tutorials online. Cleaning machines used in 4S shops are very expensive. It seems that carburetor cleaner is still used in high-rise buildings, so the back of the throttle can't be cleaned, and the cleaned impurities burn in the cylinder, causing carbon deposition.