Paragon (http://www.paragon.fi/about) for example, under normal circumstances, only raids 5 hours per day, 4 days (Wed/Thu/Sun/Mon) per week.
They also added that during farming period, it can be as low as 2-3 hours per week.
They do not practice staying up late (trust me on this, have seen this with my own eyes, they would not sacrifice sleep for a game). They allot a few hours a day for raiding and get everything done before bedtime.

Remember ForScience, the world first 85? He did mention that he was unable to log in to his server for a few hours, so he was actually set back by a couple of hours, but despite that, he managed to get world first just 2-3 hours before his closest rival.