At Hubbard you get these big pushes up Rowlett, and up the river if Lavon is releasing... If Lavon is releasing heavy you get even more fish running up. With creeks the more total flow (AKA biggest creeks/rivers) draw in the fish.
FYI sandies also can spawn on windy gravel shores (how do you think some ponds can have a population of sand bass...) On a massive lake like Lewisville a fish in the fat middle of the lake isn't going to feel a creek current, all the water moving is from the wind and/or from water releasing from the dam. Right location is key but you can find and catch fish around wind swept gravel/sand shores and points. Won't find a darn other person near you fishing for them either!