I've revisited old obsessions before, often with mixed results. I've found that "skills" based ones, like drawing, tend to be easier to forget about for awhile, and then pick up again at a later day.
TV programs, not quite as much. I found myself a little disappointed after I finally managed to watch Sailormoon all the way through a few years ago. I had been really obsessed with it for about 5-6 years, despite the fact that I'd barely even seen the series. I collected art books, manga, merchandise, CDs, made websites, wrote fanfiction, you name it... I knew all of the characters, when they first appeared, and what their personalities were like. But seeing it all the way through just wasn't as much fun as I'd imagined. I still love the series, but revisiting it didn't revive my passion like I'd hoped.
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I don't suffer from insanity. I enjoy every minute of it.