Some writers add so much detail to scenes, they lose sight of what the main point is.
I, myself, went through it recently with my debut book. I ended up deleting about 5,000 words of unnecessary detail, which in the long run benefited me, because I had gone over the 80,000 word count limit most agents recommend.
I’ve always been the over-writer, instead of sticking to crisp descriptions. Teachers usually give an amount they want for whatever writing assignment they’re giving. Usually, it’s to get kids to write enough, for me it was to know when to stop.
Over-writing isn’t necessarily a bad thing, one just has to know what to write. So, I say to you, dear reader, be careful with straying from the topic or adding unnecessary detail. Keep your sentences crisp if it’s something you can do.