User blog comment:Soulreaper1234/What's up with Ichigo and his BANKAI, is it in constant release?/@comment-1932702-20100915161534

Ichigo can keep his Bankai going until he drains out his reiatsu, which, considering it's volume, is near impossible. Although now we don't know the effects of whatever happened to his reiatsu (@any admins, sorry about this, really) if the spoiler is true.