True, to a point.
Some of these AC are like the “original” axe George Washington used to cut down the cherry tree.... They have replaced the handle six times and the head four...
Still...Most people would be amazed at what is allowed in the air.
Likewise, true to a point.
The head and handle changes apply to a lot of structures but not so much the high performance airframes... there are only so many of those.
Wings on t-38s have been changed like socks but we’re all out of socks.
Eventually the attachment points wear out as well and it is not just the 38s though they are probably the worst of the lot for having been around the longest. An airplane can only be banged into the ground so many times even though they are amazingly rugged.