I'm a bit nervous to start using it, even though I know it will be good for me. I'm very attached to my 20+ tabs and I'm not sure I'm ready to let them go after just 12 hours. As @joostschuur said maybe 24 or 48 hours would be a good upper limit so I can ease in to this.
I was made aware of this awesome Chrome Extension a few days ago. It automatically closes inactive tabs (you set the interval), and lets you grab them right back or close them permanently. It's been really useful for my productivity (and sanity).
Product Kitty