system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it that on most fans, the switch is ordered as off, high, medium, and low?

I know this is a silly question but it always puzzled me. Why don't they just do off, low, med, then high?
gpt
When you turn the fan on, the motor that powers the fan is running at max speed. When you turn the fan to medium or low, the motor is slowed down. Running the fan at the maximum speed of the motor is more efficient and the fan will last longer since the motor does not have to adjust to the increased power flow as you go from low to high. 

There is not a lot of strain on the motor when you turn the fan on, as the current flows without any limitation, and when you turn the power off, the fan stops on it's own with no adjustment of the speed of the motor. When you turn the speed of the fan down, the loss of current slows the fan down. Again, no strain on the motor.