I do this sometimes, but a lot of these players will call if they hit any middle pair on the turn or river. By checking the turn, we keep the pot small, and we're throwing away less chips on a river bluff that gets called. Plus our opponent isn't always on a flush draw after the flop action. Sometimes they are on a weak top pair or middle pair, and they're not folding unless we make a really big bet. It's close, though. Against a better opponent, someone who can lay down weak pairs, betting the turn is fine. Against a lot of the loose/passive types that I run into at low stakes, you might as well be throwing chips into the wind on the turn and river if they've happened to catch any part of the board.