Always refer to the POH/AFM for what technique to use. The takeoff data in the C172's AFM indicate that the numbers are when you use the "Short Field Technique" from Section 4. The way I teach is how the AFM says to, that is, for the C172S: Apply Brakes, Go Full Throttle, Lean Mixture for Max RPM (For operations above 3,000 feet pressure altitude), Check Power Indication and Engine Instruments in the Green, Release Brakes, Accelerate to Vr (Dependent on weight, at MGTOW of 2550, Vr=51), Hold Vx Pitch Attitude to Climb Out at 50' Obstacle Speed (Barrier Speed, again, dependent on weight, for 2550lbs, 56 KIAS) Until Clear Obstacle(s), then at Positive Rate of Climb and at least 60 KIAS, flaps up, climb out at Vy.