When God put in all my programming, He made me rather detail-oriented. I sweat the small stuff, as they say, but I also love minutia the best. It's a bit tough when trying to organize a big picture with a lot of tiny ones, though. A lot of holes go unfilled, cracks form between similar-but-not-the-same shapes, and then trying to arrange everything so it's airtight gets tough. Sometimes the wall you want to fix is the one keeping you from the solution.
People will advise taking a little time off to gain objectivity, or to regroup, or maybe just to gain insights at a less-frenzied pace. They'll say you just have to buckle down and write crap, as long as it's got you writing. They'll say print off a hard copy, or read aloud, or make a secondary copy and change the font formatting so the doc literally looks different, or to just take the bit you're having trouble with and write it in a completely blank doc so you don't feel the mental 'weight' of all the text before and after.
Those all work, and I won't say differently. They have all worked for me, in their turns. But sometimes they just don't. Sometimes you get into this funk, be it from frustration, from boredom with the whole business, from not seeing the end of the tunnel (forget the light; you can't even make out an exit strategy), and nothing makes you want to pick up where you left off before. Nothing about the prospect of continuing inspires any excitement in you, or at least not to any last, productive effect.
Everyone is different, so I can't say if stopping for any significant length of time is good or bad for you in particular, but I think you at least have to be able to give yourself a break without feeling guilty or worse as if you're failing.
Maybe it's good to have a concrete amount of time established; here if you're in a writing slump, I officially grant you one week of absolute guilt-free non-writing time. If something comes to you, jot down the gist of it, or the line or two you think of, then put it with the rest of your stuff and walk away, so at least you won't feel like you're neglecting your work. When you're that close to something, and thinking about something is that ingrained, it's really hard to STOP thinking about it. It's a a learned behavior, like worrying about your kids, or biting your nails.
It's tough. Be tougher by going easy on yourself.
Personal Note: I love make-up, but I rarely actually wear it. I see the colors, and i want them, but then I tell myself time to use them. I just purchased a new eye-shadow palette and a new eye-liner, but I've not even opened either one.