Gluttony - Overindulge or overconsumption to the point of waste.
Gluttony usually refers to food, but it can easily be a deadly sin for writer too. The phrases 'biting off more than you can chew' or 'eyes bigger than your belly' spring to mind here.
You could fall foul of gluttony if you 'bite off more than you can chew' with regard to your story's scope. A sci-fi adventure that details the private lives of the human crew on Earth, then painstakingly builds up to the launch, before describing in full the first twelve missions they undertake to a variety of planets, is likely to be a little gluttonous.
Of course the easiest way to measure gluttonous novels is in the word count. There's a reason some publishers will instantly dismiss anything over 100k words. If you're pushing towards a six figure word count it's probably worth considering either removing superfluous sub-plot or prologues and epilogues, or splitting the novel into a two parter, usually chronologically.
A novel's scope can be difficult to reign in, but a focussed novel will always read better than an unfocussed one. If you can't distill the essence of your story into one or two sentences you'll struggle to pitch it to publishers and agents anyway. It can feel offensive sometimes to be told your novel is a 'boy meets girl, they fall in love' story, especially when you have twists and sub-plots that are so important to the eventual conclusion. The ability to understand what it is you're trying to say through your characters is nonetheless important and helps you to strip away the added fat that doesn't contribute to the basic premise.
One reason that a series of novels works so well, is that it allows an author to focus on the individual story of each novel, while only providing small amounts of patchy information about the main characters. If you want to give lots of history of the town your novel is set in, or the past life of the main character, consider whether the reader needs to know all of that in one book. Revealing character back story across a series is both satisfying to the reader and a good way to tackle gluttony.
So when planning your next novel, focus your eyes on the main course, only reveal bite-sized pieces of back story, and always leave the reader hungry for more!