brush maintenance realy IMO depends on what type of brush and spring you run. I have found that it isnt necasary to rebuild a motor after 3 to 4 runs when using F brushes and red springs on the + and -. he break in and buid is critical to what type of maintenance you will have to do and how long your brushes will last. When I build or rebuild a motor all I do is put a slot verticly on each brush put some comm lube Tribo or zubaks on the face of each brush then lightly oil the bushings and break it in @2 volts for 15 min. By doing this I have been able to run a set of brushes for 12+ runs without any noticable drop in performance in fact I have seen gains after 4 to 5 runs. For maintenance All I do is after 3 runs I check the brushes for wear and that the comm is wearing the brush face evenly this would indicate if the hood is in proper alignment with the comm then I clean the motor with motor spray and using a comm stick clean the comm and brushes so they are shiny but also pay attention to the hood making sure anywhere the brush contacts the hood is clean as well then I put a drop of comm lube on each brush and lightly oil the bushings and run @2volts for 2 min and then it's ready to race ...
Now with 767 or 4499's I would still replace after 4 to 5 runs I have noticed a difference in performance with both and have always got more from a fresh rebuild with them.
I have not yet to try the lemans xxx brushes so I wouldnt know where to start with those..