In my non-writing life, I'm not a pack rat, I'm a purger. I have a Goodwill donations bag going at all times, and I relentlessly thin the morass on a regular basis.
I will admit that moving frequently helps. No place for that thingamabob in the new house? Toss it. ;-)
However, in my writing, I horde and reuse scenes as if they were precious heirlooms. On my current WIP, I took out 20,000 words, and nearly started over, but I didn't toss those scenes. Instead, I moved them into my unused scenes folder (Scrivener makes this super easy), and raided them (the pirate part
Heck, I poured hours of effort into those words. Why not repurpose them, if possible?
Even though my plot went in a different direction, there were perfectly good elements buried in those deleted scenes. With a few tweaks, the sex scene in the bedroom could be brought back wholesale. A part where I described the scenery as they drove north fit perfectly into a later scene. (The reason they were traveling changed, but the scenery didn't.)
Sure, most of my hard-earned prose is destined to stay in the dustbin, but there's no reason not to recycle when it works. And for the rest of those words? Writing is never a waste of time. It's part of the learning process. Every word gets us closer to the one million mark.