At around the 2:45 mark of the video of Norm MacDonald roasting Bob Saget, he tells a ridiculous joke about Saget looking "like a flower...yeah, a cauliflower" and he then repeats and somewhat explains the joke. Not a stand-up comedian, it is my determination that MacDonald does this repetition/explanation to hammer home just how absurd this joke (and the others in this fantastic routine) was. In other words, he HAD A REASON to do so.
Maybe my biggest recent pet peeve in reading is when an author does NOT trust their own writing, or apparently believe that their reading audience is of a junior high school level or below. After writing a beautiful passage, with a nice subtle point to it, they'll follow that passage and period up with the explanation. WHY??? Why not trust that you've made the point with your writing? Why not believe that the person reading your work has the ability to piece together what you've sewn?
I'll show no example of this as it would be incredibly rude, but I think it's something younger writers especially should pay attention to--TRUST YOUR WRITING//TRUST YOUR READERS--it will make your work stronger.