Also, for the spirit bond method, make sure you are using gear that has materia slot(s) and do fill them with materia, any materia, even L1 materia.
The reason is that gear that doesn't have materia slot(s) or isn't melded will spirit bond at a much lower rate than gear that is melded.
Then, as advised above, hit the high level nodes with +spirit bond medicine and you will start spirit bonding extremely fast, making new materia every several nodes.