I just read an article (published in 2012) telling the special livery for British airways' A320 to celebrate the Olympics game is made to last one year. I assume this mean those aircraft are painted once per year because painting is not free and thus it is reasonnable to change the livery only when painting is already schedule. But because this is a special livery, it may last less than other painting. As this is only assumptions, my question is the following:
How often is an Airbus or a Boeing painted (even without changing the livery)? Does it significally change from on airline to another? Does a special livery change this frequency?