How to utilize/calibrate print fans for PLA?

Fan Fails to Start

How to configure Marlin to enable auto-fans with dual extruder

Is it advisable to use additional external fan(s) for printing PLA?

Understand what CR-10S fans are cooling

Cooling fan noise when head is moving in the X axis

Why turning off model cooling for first layer?

Cooling fan spins extremely fast, noisy on startup