The procedure that I use in brush development is that I use a Hake brush. I first presoak the negative in a water bath. Then I place the negative emulsion side up in the developer tray and move the brush in much the same way that I would if I were painting the negative (lightly)... covering the negative in straight lines from one side to the other. When I am finished covering the entire sheet this way I then brush at 90 degrees to the first "pass". When finished with the 90 degree pass I then return to the pattern of the first pass.
The advantages are the most evenly developed negatives possible with the least possible damage. The disadvantages are the length of time processing one sheet at a time. However, I really think that the extra time spent in developing this way is offset by the absence of damaged negatives, the evenness of the development, and the ease of printing the properly developed negative. When I get impatient, I think that Edward Weston most often developed his negatives one at a time. There certainly is no arguing with his results. Not for me anyway.
Yes, one can brush develop by inspection. Just inspect the film to a green filtered 15 watt bulb at 75-80% of the expected development time.