Thanks for the info. My wife's 04 Aveo was having the same issues with the front pads being ok but low pedal and barely any stopping power. I did the reversing and stomping on the brakes method and now the car stops on a dime. This car was under-engineered in many ways. I can't believe there was no access hole in the back of the brake drum to adjust the rear brakes.
The "reverse fast, then stomp brakes" technique worked for my 2008 Aveo sedan. After a rear brake cylinder replacement, my brakes were weak and wouldn't bite, and the pedal would engage only about halfway down to the floor. This was after a thorough brake bleeding. After trying out the technique, the pedal engages early, and stopping power has returned. Many thanks.