There is no set weekly frequency of masturbation for adults that is considered "normal." Some people masturbate frequently, others occasionally, and some not at all—it depends on each individual's sexual needs and circumstances.
More important than the frequency is whether it is affecting your daily life. If you are able to manage it and it does not negatively impact your sleep, work, studies, relationships, or sexual functioning, then it is not considered a problem based solely on the frequency.
If you struggle to control the urge or if the habit interferes with your daily routine, seeking advice from a professional can be helpful.