That's a standard rule of screenwriting, and I think it applies to commercial fiction as well. I majored in TV/Radio (...yeah) with a minor in Screenwriting, so you'd think that rule would be tattooed to my brain, but I had to re-learn all the old script edicts once I started writing novels.
It's hard somtimes to cut to the heart of a scene. We fall in love with certain descriptions, background info, or dialogue, and it pains us to cut it.
But here's the thing: the reader will never know it's missing.
Have you had any epiphanies about shorter scenes? Have you removed whole chapters, or fought to keep something in?