Fleeting was a social practice by Culture ship Minds where ships operated in close proximity to each other. This reduced the inconvenience of signal transmission lag over interstellar distances. Fleeting was very operationally inefficient.
Fleeting continued to gain popularity amongst relatively young Minds in the 19th century. The practice drew criticism from some older Minds who disapproved of the sacrifice of operational efficiency for convenience; they suggested modifications to the premise-states of new Minds to reduce future instances of Fleeting.