In my last few MOT's i have had brake caliper sticking issues. I asked my local mechanic about this. His reply.
"Every now and then, find a bit of quiet road, speed up to 60 mph (ish) and slam the brakes on. Do this a few times"
He reckons that people using their gears to slow down, and a general steadiness in modern driving is leading to more and more calipers seizing.