The National Congress is the supreme legislative body of a country, responsible for making laws and representing the people. To provide an accurate answer regarding the number of times a specific National Congress has held its sessions, it is essential to know which country's National Congress is being referred to.

Different countries have their own National Congress or similar legislative bodies, such as the United States Congress, Indian National Congress, National Congress of Brazil, etc. Each of these entities has its own history and specific session details.

However, if we consider the most prominent National Congress, which is the United States Congress, we can provide some information about its sessions. The United States Congress consists of two chambers: the House of Representatives and the Senate. These chambers hold separate sessions, but they also come together for joint sessions on special occasions.

Here are some key details regarding the sessions of the United States Congress:

1. First Session:
- The first session of the United States Congress was held in New York City on March 4, 1789.
- This session marked the beginning of the legislative activities of the newly formed federal government under the United States Constitution.
- The first session concluded on September 29, 1789.

2. Subsequent Sessions:
- The United States Congress has continued to hold regular sessions since its inception.
- Each Congress is divided into two-year periods, known as "sessions."
- Generally, a new session begins every two years on January 3, following the biennial elections held in November.
- For example, the 117th Congress commenced its first session on January 3, 2021.

3. Special Sessions:
- Apart from regular sessions, the President of the United States has the authority to call special sessions of Congress.
- Special sessions are usually convened to address urgent matters or crises that require immediate legislative action.
- Special sessions can be held in addition to the regular sessions and are called at the discretion of the President.

It is important to note that the number of sessions held by the National Congress of any country may vary based on the specific country's legislative practices and constitutional provisions. Therefore, to provide an accurate count of sessions for a specific National Congress, it is necessary to specify the country in question.