You may find that on some lakes if the bars are flat, is that fish will feed on bait on top of them. They may be wary (hence the 'need' to change rigs), but because so much bait goes on top they will eat it.
The same lake may also have fish that are caught from the bottom of the bars, as natural food, and short or long fall baits that don't land on the flat will fall into the troughs.
Some more food for thought though:
How many people think that they are fishing on top, but are actually dropping short with the swing of the lead?
Reeling in 'excess' line should tell you if you are hitting the clip and tightening up, by 1 or 2 reel handle turns as opposed to 10...