Though looking back at the shows I rated 10/10 on MAL, except for Space Bros it all doesn't feel like a 10/10 anymore. It did when I watched it, but in my memory how well I enjoyed the show quickly becomes distorted. And Space Bros is a show I gave a 10/10, not because it was a masterpiece in terms of plot or animation or anything, but purely because it was able to keep me entertained every Sunday morning for two full years. If I'd watch it in a marathon it'd be an 8/10 at best.
That is why I update these score from time to time. Most of the 10/10 shows still hold up pretty well :|