As TV Tropes would have it the
Ten Minute Retirement, where the main character decides they will no longer do what the series is about. No heroics for them. And of course it usually ends with them getting back in the saddle by the end of the episode and hero0ing up. Which means their previous hestiancy was just a big ol' waste of the watchers time.
I remember being especially annoyed with this mid-Series 7 of Doctor Who, it didn't help that his impetus for his retirement was the loss of his companions, Amy and Rory, in an equally horribly contrived episode.
But mostly this post is brought to you by Walter White who has started and stopped cooking meth at least three or four times by episode 2 of season 3.