Looking at the Simpsons Wiki it says he pops up a few more times in crowds, plus an Artie episode where all his characters show up (I think he makes a joke about how nice their voices are).
He does then show up properly in much later seasons, so I guess seldom appears.
![He is crushing your fragile point [Simpson, Eh?]](https://lemmy.world/pictrs/image/8fd09551-bfc1-4969-aa1b-14046ff0300b.gif){kind=link}
Looking at the Simpsons Wiki it says he pops up a few more times in crowds, plus an Artie episode where all his characters show up (I think he makes a joke about how nice their voices are).
He does then show up properly in much later seasons, so I guess seldom appears.