You come home to a hot house. The thermostat reads 82. You want it at 74. So you set it to 65, thinking the system will work harder and cool the house faster.
It will not. The house will reach 74 at exactly the same time regardless of whether you set the thermostat to 74 or 60.
Why
Your air conditioner has one speed. It is either on or off. When the thermostat calls for cooling, the compressor starts and runs at full capacity. It does not have a "turbo" mode. Setting the thermostat lower does not make it run faster, blow harder, or produce colder air. It just tells the system to keep running past 74 — all the way down to 65, or wherever it can reach.
The result: you forget about it, the house drops to 68, and you have wasted energy cooling the house 6 degrees below where you actually want it. Then the system has to cycle off and let the house warm back up. You paid for cooling you did not want.
The exception
Variable-speed systems (inverter-driven mini splits and some high-end central systems) do modulate their output. A larger gap between the set point and the current temperature causes them to run at a higher stage. But even then, setting the thermostat to 60 instead of 74 does not make them cool faster in a meaningful way — the difference in ramp rate is small, and the overshoot cost is the same.
What to do instead
Set the thermostat to the temperature you actually want. The system will run continuously until it reaches that temperature, then cycle to maintain it. If you want the house cool when you arrive home, use a programmable or smart thermostat to start cooling 30 minutes before you get there. That achieves what you actually want — arriving to a cool house — without the energy waste.