Martingale should NOT substitute the correct training. I have no problem with martingale adjusted correctly when it's used to protect rider's face from being smacked. However I don't think using martingale to "teach" horse a "head-set", "self-carriage", or whatever else is a right way to go.
"Life isn't about waiting for the storm to pass: it's about learning to dance in the rain..."
"When we are no longer able to change a situation - we are challenged to change ourselves."
"How people treat you is their karma; how you react is yours."