when should i give up on anti-lock sending unit repair

What is your question?

My mechanic has repaired the brakes but the brake light comes on , the brakes are grabbing without being applied, they will not let go until the car sits for a while. The mechanic has replaced the wire that shows one of the brake calipers is activated. I am wondering if it is practical to continue replacing one wire at a time hoping that the next will be the last problem. My mechanic says there are 3 of these wires (sensors ) on each brake. The first repair was $250 but the implied potential is that all 3 on each wheel should be replaced. since the brake light has come on twice in several hundred miles since replacing the first wire (or brake light sensor), how much patience should I have?