Prodigies: How Fast did they graduate from Shinigami Academy (6 Years Designed Curriculum)

For Context,

Shinogamy or Shino Academy's Curriculum is designed to be completed normally in 6 years.

However, gifted and genius prodigies can graduate early.

Known Fastest Shinigamis to Graduate in The Academy:

Toshiro Hitsugaya: 1 year

Gin Ichimaru: 1 year

Kaien Shiba - 2 years

Shino Academy is like the School for amateur/student shinigamis. They will be taught all kinds of knowledge and training. From Fighting, Kidos, Zanpakuto, And even general subjects like Calligraphy, Haiku, medicine, etc.