Websudoku question.

[BeerMoney]

It seems there puzzles are always symmetric. Can anyone tell me why this is?

What % of the population could solve an evil puzzle within 2 hours? (With being familiar with the game.)

[DoomSlice]

I've solved an evil in much less than that, and I only had one easy and one hard as prep.

So my guess is that quite a large % of the pop can do it in under two hours.