The amount of juice used varies with your actual vaping habits and the type of atomizing device you are using.With that said it is possible to get pocket activation(firing) that will cause more juice to be vaped and/or atomizer(cartos etc) loss through over firing or dry firing.When I first trying ecigs even the auto batteries I had at the time would activate at the slightest bump,but this was 3 or so years ago.I personally prefer manual batteries that have a shut off function eg ego batteries and various if not most mods.
hope this helps