I am aware of the long-standing customs of which you speak.
Iris wouldn't be so rebellious if it were a long-standing custom.
There is a long-standing custom of standing after verse 9 in Handel's Messiah.
It was the long-standing custom of noble Persians to bring their families to the field of battle.
This decision upheld the long-standing custom in America of state governance of corporations.
Our lives were regulated less by laws than by long-standing customs and traditions.
"I am in conformity with canon law and with long-standing custom, while you set established practice on its ear."
But this would be insufficient reason to change long-standing customs and policies.
However, this is a long-standing custom in the country.
The exchange of gifts between rulers is a long-standing custom.