when hanging less then 5 doors, i use the makita trim router free hand, i trim to within 1mm of the pencil line, and finish the rest with a freshly sharpened chisel.
any more than 5 doors, i bring out the hinge jig, similar to what has been described by holzhacker, only mine is aluminium.
as you have 6 doors, i recommend using the mfk 700 free hand and finish off with a chisel.
i also use the modern method of measuring 200mm (8 inches) down and 200mm up for the placement of the top and bottom hinges. as opposed to the old school method which was 6 inches down (from the top) and 9 inches up (from the bottom).
i am interested to hear if anybody else has their own preferred measurements for hinge placement?
regards, justin.