I work at a Toyota dealer, we do lots of brake flushes. We have a Wynns X-tend machine which pressurizes the M/C, and has a recovery hose that goes on the bleeder screw. Several minute flush on the right rear to replace the fluid in the master and RR caliper/cylinder, two minutes on the rest of the wheels. It is definitely a part of the maintenance program.
So how much new fluid is used to do a flush like this? several minutes at each bleeder with a pressurized system sounds like it could be several gallons of fluid.
