Andy, there is a curve. More flaps give you more lift to a point, then they produce less lift and more drag. Usually, the optimum is around TO flaps. THat is also why, when you have a deadstick, you go to TO flaps, to maximize your glide ratio

But at landing flaps, usually there is less lift. You want the induced drag, plus the flaps will make the center section of the wing stall first, keeping the wingtips flying and avoiding tip stalls.

The reason you want to go full flaps, full speedbrakes on a dirty flyby, is because you can get on the side of the curve where your airplane flies on the power (high alpha type of flying).