long-standing

adjective

Having existed for a long time; of long standing.
“Forty-five years ago, Crewe was witnessing the first year of the revised timetable associated with the 'Electric Scots' services, following inauguration of through London-Glasgow electric running in May 1974. Except for Euston-North Wales traffic, the long-standing practice of motive power changing at Crewe had ended.”
““As soon as I am inaugurated, I will direct the Justice Department to vigorously pursue the death penalty to protect American families and children from violent rapists, murderers, and monsters. We will be a Nation of Law and Order again!” Trump wrote on Truth Social, echoing his long-standing advocacy for use of the death penalty, which was part of his tough-on-crime rhetoric during the 2024 campaign.”
Having been done for long enough time to become convention.
“Long-standing custom calls for referring to the town chairman as mayor, even though we don't have a mayor.”