Dave,
Most times it is the horizontal sections, each side of the 'vertical' bar, that fall off.
I have found that if you brush the window glass 'side to side' and don't use any 'up and down' strokes, they usually stay put.
(I assume it is because the 'sticky tape' on horizontal bars are 'affected' more by rain water resting on them, soaking into the tape and weakening/diluting the glue)
Try it.
Mike