Look for differences within the mat such as where two different weeds meet. Look for stumps or cat tails within the mat and punch toward the base. If there is current punch the weed "points" as sometimes they ambush from the outside. Pump your bait slow, faster, let it sit on the bottom even or pump it up and down only a few inches from the top. Eventually you could figure out a pattern. If you feel anything set the hook right away.