But they are never driven from the hardware PWM pins.
Some of the documentation for the subject board states the following:"All channels must have the same PWM frequency. For LEDs you probably want 1.0 KHz but servos need 60 Hz."
Here's the "crap documentation" that I quoted from: https://learn.adafruit.com/16-channel-pwm-servo-driver/pinouts
Question is: what do YOU want to do.LEDs or servos.