The hinge markings are transferred from the doors to the cabinet to maintain accuracy.Creating the hinge mortises with hand tools is somewhat of a pleasant task although it can take a while. Care needs to be exercised with grain orientation as the grain is reversed depending on which corner of the cabinet is being mortised. I use both chisel bevel down and back down orientation to remove waste from the hinge recesses. The outline of the hinge and its offset from the edge of the cabinet and doors is fairly important.
Once this is accomplished, removing material from the recess is fairly foolproof. I remove wood from the hinge recess in stages, exercising care not to go too deep in one pass of the chisel.