Many major sporting events are held every 4 years such as the Olympics, Football World Cup, UEFA European Championship, Rugby World Cup, etc.
I've had a look around and I've yet to find an answer that isn't personal opinion or is backed up with a source - one site also said that there is no evidence as per why the Olympics is held once every 4 years.
The Olympic games registration website's FAQ states that it is held every 4 years to respect tradition, but that leaves the Fifa website does not offer a reason why the world cup is held every 4 years. Is it a case that they followed the model of the olympics for traditions sake?
To respect the ancient origins of the Games. At that time, sports competitions were organised in Olympia and were named after their location, i.e. Olympic Games. These Games were held at the same place every four years. This four-year period acquired the name Olympiad, and was used as a date system: time was counted in Olympiads, rather than years.
So, since when have these major sporting events been held every 4 years? The decision to hold them every 4 years may have been relevant due to the pressures of the era in which they begun, transport limitations, foreign policy etc.
To be clear - I am specifically asking about why the trend developed. I'm working on the assumption that the 4 year gap was not arbitrarily decided on and while the Olympics may be on a 4 year cycle to respect tradition/the origins of the tournament other tournaments with the same gap cannot share this reasoning. Research on the beginnings of the Football World Cup may present a reason for the other tournaments sharing the same cycle e.g. Spread financial pressure, it wasn't viable for athletes to gather more often due to transport, it's an acknowledged tradition in the sporting world established by the Olympic Games.