I always wait, for every drama. There's no way I'll do it piecemeal - not with them putting cheesy cliffhangers at the end of practically every episode. A season's much better consumed in a 2-3 night binge.
@Gazza and Qs - The fundamental problem with the show is that Walt's descent is pretty much complete now. If I was writing the script I'd change the tone completely - instigate a massive crisis in the dramatic status quo (e.g. Walt causes the death of either Jesse or his whole family) - and then make the rest of the show about Walt's slow journey to total redemption.
It'd rate terribly but at least it'd be literature, and since the show's only themes are ethical behaviour and family that's all the material they have to work with.