I know it's not Sky's fault. If they decided to air it on the same day (would have to be 6 or so hours ahead in the UK to time zone) then I don't see a problem, why would the producers/yanks go off it?
If they done that they would be showing the program in the middle of the night.
Instead they have to decide on a time that they think would be best for showing it.
For Sky as an example with Season 3 the US it was shown on a Monday, and Sky showed it the following Sunday.
The US now show it on a Friday, which is perfect for Sky One, as they can show it on the Sunday as they did behind the US.
I cant find it at the min but there is a Wiki and a few other sites the have details about it all that ie for us the UK have to show the progs after it has been show in the UK.
The time zone 6-8 hours between the US and UK would mean if they it was aired even a few hours after them would mean they would air in through the night,