I have definitely observed that juice flows in whichever direction gravity takes it.
If you leave your cartridge attached for a long period of time without using it, like overnight, then I think you may experience one of the following two issues...
1) Leave it sitting cartridge side up and you might flood the atomizer overnight
2) Leave it sitting battery side up and you might have no juice for your morning vape
I always blow out my atomizer every morning and clean the battery connections with a tissue.
This takes about 20 seconds and one single square of toilet paper.
And then I know I have all the old juice out of there.
And I put about 6 drops in to start the day.
After that, two or three drops at a time as needed.
Works GREAT for me.
