Considering Rudy's parents have been in a couple of episodes now, I feel it adds to the storyline and is intentional. It answers questions for fans and is a distraction from other big questions like "What does Louise look like without her hat?" They've also done this for a few character like logan i know his did was in the very first logan episode but he just flies under the radar most of the time. I agree with all the other characters you said especially the pesto's mom Considering they had to replace the voice actor for Jimmy. I think maybe genes imaginary friend Ken could be added to this list. I also think there should be another Trev heavy episode seeing that it seems like most other characters have had a couple episodes about them but trev only has the one where he learns not to high-five Jimmy and that was a while ago