Question: How often were the games who the Arrephoros worked to prepare the peplos for held?

Context paragraphs:
List of multi-sport events: A multi-sport event is an organized sporting event, often held over multiple days, featuring competition in many different sports between organized teams of athletes from (mostly) nation-states.  Events are typically held over a few days to accommodate the large number of events held, often more than those in single-sport competitions.  The first major, modern, multi-sport event of international significance was the modern Olympic Games.  Some of the most recognised sporting events in the world today are multi-sport events — the World Games, the Commonwealth Games, the Pan American Games and the Mediterranean Games — among others.  This article lists all major multi-sport events, whether defunct or functioning, in the modern day.  A full listing of all major multi-sport events is provided in the table below.

Tabagie (feast): Tabagie is a Mi'kmaq word, often found in historical descriptions of solemn feasts in Quebec and Maritime Canada.  A tribal unit would call a "tabagie" to observe a solemn event, such as (but not limited to) the imminent death of a senior tribal member.  The term is also found in "The Voyages of Samuel De Champlain", as Algonquins prepare to "put to death their prisoners in a festive tabagie".  On 27 May 1603, a solemn tabagie or "feast" held at Tadoussac "reunited the Frenchmen Gravé du Pont and Champlain with the Montagnais, the Algonquins, and the Etchimins," and marked the beginning of an enduring alliance between these peoples.  The term may be derived from "tabac" (tobacco), which was smoked as an essential element of the ceremony of the feast.

Yiannos Papantoniou: Yiannos Papantoniou (Greek: Γιάννος Παπαντωνίου ; born 27 July 1949) was a member of the National Parliament in Greece (MP) from 1988 to 2007, Minister of National Defense (2001–03), Minister of Economy and Finance (1994–2001).  During his time as Economy and Finance Minister, he worked closely with his Economic and Financial Affairs Council partners to prepare for the launch of the Euro in Greece.  For his achievements he was ‘highly commended’ by "Euromoney" magazine in September 1998 as Finance Minister of the Year.  Prior to this, Papantoniou worked at the OECD (1978–81), served as a Member of the European Parliament (MEP) from 1981 to 1984, and as Advisor to the Greek Prime Minister on EEC Affairs and Integration.  He was elected as Chairman of the Board of Governors of the European Bank for Reconstruction and Development (EBRD) in 1999.  From 2009–10, he was Visiting Senior Fellow in the Hellenic Observatory within the European Institute at the London School of Economics and Political Science.  Papantoniou has published numerous articles and books on topics related to economic and political developments in Greece, Europe and the wider world scene.  In November 2014, Papantoniou was convicted by an Athens court of failing to declare 1.2 million euros in a Swiss bank account held under his wife's name.

Watchnight service: A watchnight service is a late-night Christian church service.  In many different Christian traditions, such as those of Baptists, Methodists and Pentecostals, watchnight services are held late on New Year's Eve, and ends after midnight.  This provides the opportunity for Christians to review the year that has passed and make confession, and then prepare for the year ahead by praying and resolving.  The services often include singing, praying, exhorting, and preaching.

Handstand push-up: The handstand push-up (press-up) - also called the vertical push-up (press-up) or the inverted push-up (press-up) - is a type of push-up exercise where the body is positioned in a handstand.  For a true handstand, the exercise is performed free-standing, held in the air.  To prepare the strength until one has built adequate balance, the feet are often placed against a wall, held by a partner, or secured in some other way from falling.  Handstand pushups require significant strength, as well as balance and control if performed free-standing.

Teufaiva Sport Stadium: Teufaiva Sport Stadium which was previously known as "Tenefaira Field Stadium" is a multi-purpose stadium in Nukuʻ alofa, Tonga.  It is used mostly for rugby union, football and rugby league and the Ikale Tahi team matches.  The stadium holds 10,000 people.  It is the home ground of the Tonga national football team.  Teufaiva is where the Secondary School sports in Tonga are held (every year).  Also, in 2019, Tonga will be hosting the Pacific Games there.  In January 2015, it was announced that the stadium would undergo a reconstruction to prepare for the 2019 Pacific Games.

Arrephorion: The Arrephorion was a small building sited beside the north wall of the Acropolis of Athens and next to the wall of Pericles, identified in 1920 by the German architect Wilhelm Dörpfeld.  It provided the lodgings for the Arrephoros, four noble Athenian girls who worked to prepare the peplos which would be used in the Panathenaic Games.

Ecstasy of Order: The Tetris Masters: Ecstasy of Order: The Tetris Masters is a 2011 American documentary film that follows the lives of several gamers from around the country as they prepare to compete in the 2010 Classic Tetris World Championship held in Los Angeles, California.  It recounts the development and rise of Tetris as one of the most-played video games of all-time, the role it has played in shaping the lives of the gamers it chronicles, the mystery surrounding the whereabouts of former Nintendo World Champion Thor Aackerlund, and the conception and execution of the first ever Classic Tetris World Championship by gaming enthusiast Robin Mihara.

Doris Brown Heritage: Doris Brown Heritage (born September 17, 1942) is a retired American runner.  She won the International Cross Country Championships five times in a row, in 1967–1971, and collected two silver medals in the 800 m at the Pan American Games, in 1967 and 1971; she placed fifth in this event at the 1968 Summer Olympics.  Brown briefly held the world record in the 3000 m in 1971.  After retiring from competitions she had a long career as a running coach, and helped prepare the national women's team to the 1984 Summer Olympics.  She was inducted into the National Track and Field Hall of Fame, National Track Coaches Hall of Fame and National Distance Running Hall of Fame.

Panathenaic Games: The Panathenaic Games were held every four years in Athens in Ancient Greece from 566 BC to the 3rd century AD.  These Games incorporated religious festival, ceremony (including prize-giving), athletic competitions, and cultural events hosted within a stadium.

Supporting paragraphs: Arrephorion Panathenaic Games
Answer: every four years