User blog comment:Soulreaper1234/What's up with Ichigo and his BANKAI, is it in constant release?/@comment-44061-20100915050543/@comment-44061-20100915060618

Shikai and Bankai correspond to forms of the Zanpakuto, whether or not someone uses all their reiatsu at its fullest is unknown. What is known that bankai or big and powerful and consume alot of energy to use. Ichigos smaller one compresses allowing him to maintain it longer. Hitsugaya has never shown a problem with his bankai is second only to ichigo in the number of times he has used bankai. There is no point in the series to compare them in amount of time used. Ichigo's compression of his reiatsu is not due to him its the nature of his bankai's ability, so it would affect him no more then anyone using a zanpakuto's ability.