If I am not bouncing bottom BEFORE my presentation is passing through the slot I am targeting then I make adjustments. I first try casting farther up stream especially if I am casting across a lot of water. Then I will add more lead if needed. Sometimes though there are obstacles that do not permit me to cast up river farther and I may move down stream a little or add weight. Reguardless of what you have to do the point is to be bouncing bottom through as much of the targeted area as possible. I personally like to bounce pretty hard through fast water to slow my presentation down which allows the fish more time to react and grab whatever it is that I am offering them.