Honestly, I got really bored of it really quickly. The constent adds sped up the proccess I guess. Also, Zan comes from every other Shin Megami Tensei game that isn't Persona.

Most games either use Zan or Garu. Well, Persona most of the time uses Garu instead of Zan, but this isn't always the case. P1 had both Zan and Garu, though that game also had everything under the sun. For some reason they decided to add a fuck ton of new elements, which technically includes Garu. Generally Zan is considered a 'non-elemental force' series of skills, not being based off of wind but damage through a sudden, forceful impact... though most of the modern games show Zan as basically just being wind, in some games Zan/Force skills could be things like violent explosions. I think P2 actually classified Zan as Almighty even. Anyway Zan and Garu refuse to coexist after P1.