I've actually been struggling with the same thing lately. I have way too many games that I started but never finished, because I always get distracted by new releases. So when there aren't any new games coming out, I tend to go back and try to continue the ones I left halfway through.
It feels like a bad habit sometimes—so many games I've never properly finished. When I do go back, I usually check how much I still remember about the story before deciding whether to restart or just continue. Because even if I do start from the beginning again, there's still a chance I might end up dropping it halfway again.