The pads and rotors on my rears are only a couple months old. Right before I did this brake job, the handbrake was very tight, and suddenly it's way loose. This isn't just due to wear.
then another possibility is your e-brake cables are worn out, on lightshow's silver SVT, the e-brake cable would pull up very high, but still engage, right after doing his motor install, we parked the car in the street, I cant remember who but one of us pulled the e-brake lever up, and the cable snapped, so now its super easy to pull, and it doesnt do anything at all.
Common for the e-brake cables to go bad on the contours.