Eric:
Thanks.
I monitor my remaining pad friction material pretty religiously. For two reasons, keeping the brakes fit, and getting the most out of my pads before replacement, so I let the friction mater get pretty thin, but not so much to activate the squealers.
As the friction material thins the pin sliders extend more from their holes and are more likely to bind if slightly imperfect regarding lube, dirt, rust.
With respect to all….