Question for ThermaCell owners

How far gone do you allow scent pads to get before you replacement them? Have you noticed any drop in effectiveness if you try to make them last longer? I seem to remember seeing somewhere you're supposed to replace them once they show faded white lines, but how much white do you want to see in a pad before you replace it?

TIA

When it is almost completely white, I replace it. I have not really noticed any drop in effectiveness until it is mostly all white.

I've been tossing mine far too early.

This

When ya start seeing skeeters or ya getting bit, change the pad.