Cupcake:
The things I rate 10s are series that:
1. Kept me entertained the WHOLE way through
2. Made me feel really happy and had little to no flaws for me.
I'm the type of person who can't rewatch ANYTHING too often, or too close together, no matter how good. If I do it'll get boring. For example KP, absolute perfection in my eyes, yet I haven't rewatched it (even though I want to) and probably will wait a while before I rewatch.
I also want to rewatch KP. I think I might like it more as a binge instead of watching it weekly. It might be a rare re-rate that goes higher! As far as rewatching other things, I could watch Semantic Error or Wish You over and over again with no trouble. Otherwise I wait until I am possessed by the urge to rewatch a particular drama.