I've never bled Hayes, but Allison has had Avid's on her last 2 bikes and so do her friends so I have bled them lots.
they have a procedure with two syringes (one in caliper, one in master) and you push fluid from the caliper to the master. We probably bleed her brakes 3 times a year just because it is easy bike maintenance. Her friends take much worse care of their bikes and we bleed them at trail heads and stuff when it's been over a year that they did it last. we all ride probably every day so it may be a more extreme case.
As far as pad wear it has a lot to do with how you ride and what terrain. muddy, kills pads.