Sure? I think a battery drain happens in BIOS 3.07 or earlier. See Battery slowly drains when completely shut down . And it seems it was fixed on 3.08.
Because I am lazy to shut down. Sleep is convenient to continue to work even in a short down (spare) times. I want to keep opening terminals and browsers related to developing, reading or writing work. I find down time, then work on it. I find another down time, then work on it again. The down times are such as ones for waiting a food in a restaurant or a cafe, or waiting or getting on a train or airplane.
Or even at home, I start to use a laptop, then I stop a laptop, then start to read a book, then start to use a laptop again, then stop a laptop and start to eat something… Sleep is good.