been there, done that, or seen one, seen them all

Concert Hour: Deutsche Welle Festival Concert

Telemann Festival in Magdeburg: The world of classical music isn’t always
a case of ”been there, heard that.” Even with major composers,
discoveries lie ahead.

The DW-WORLD Article
http://newsletter.dw-world.de/re?l=evyw5qI44va89pI1

Idioms:

seen one, seen them all

One example suffices, as in I'm afraid I don't care for home movies--seen one, seen them all. This world-weary expression was first recorded in 1811.

A newer idiom expressing a very similar view is been there, done that, indicating that it is boring to repeat an experience once it has lost its novelty.
For example, No, I don't want to climb Mount Washington; been there, done that. This idiom was first recorded in Australia in 1983 and was popularized in America in the 1990s through a widely aired commercial for a soft drink.