What are the main causes of inaccurate timekeeping in automatic mechanical watches

There are two main reasons for inaccurate timekeeping in automatic mechanical watches:

Firstly, quality issues with the watch itself, such as failure of the automatic winding mechanism or malfunction of the oscillating weight, both of which can cause inaccurate timekeeping;

Secondly, there are issues related to consumer usage. The former can be determined through testing by relevant national inspection departments; if it is a quality issue, the merchant must provide a refund, exchange, or repair according to regulations. The latter depends on the specific circumstances of the consumer's use, such as who is wearing the watch and the environment in which it is worn.

Reasons for inaccurate timekeeping in automatic mechanical watches caused by consumer usage include the following:
Insufficient physical activity by the wearer can result in the automatic watch not being fully wound, leading to the watch running slow or stopping. This type of watch is not suitable for the elderly or those who work in offices and have low levels of physical activity.
Exposure to magnetic fields, such as those from televisions or mobile phones, can cause the watch to keep inaccurate time.
The wearer themselves possesses a relatively strong human magnetic field, which affects the timekeeping of the watch.