The number of treatments needed to resolve symptoms differs for each individual. This is affected partly by the nature of the issue, and partly by how long it has been affecting you. Generally, patients come in for acupuncture once a week for the first 4-6 weeks. These early treatments are cumulative in nature, and most effective when reinforced on a regular schedule. After this time, you and your practitioner re-evaluate together and determine how treatment should proceed based on the results of the initial sessions. Many people choose to continue treatment bi-monthly for a few weeks, slowly increasing the time between treatments as time goes on. Often, patients choose to continue treatment seasonally after all symptoms have been resolved to keep themselves at peak health and prevent symptoms from returning.
If you're interested in learning more about acupuncture treatment plans and how this effects the number of treatment needed, an excellent article on the topic can be found here: Acupuncture Treatment Frequency.