Sasha-I never needed to shake mine.
When I open it ,there always seems to be enough powder in there.
BTW, when you put the lid on, the brush should be in the lid not in contact with the powder at all. So I'm not sure why your getting powder on the brush.
Oh yeah the bruch goes the right way up coz you have to screw it on. i mean when you shake it before you open it. When you do opwn it all the powder is on the underneath of the brush. does that make sense??
But even shaking of the excess powder of the brush this morning I still has a sink full of duct. :)