Ichigo's Bankai increases all his abilities Ichigo's Bankai works by compressing all his massive energy into a compact form. This makes him exponentially faster, his hits are harder, and his abilities such as the Getsuga Tensho are increased in power and damage as well. Also, because his power is being compressed, not expanded, he can use his Bankai for very long periods of time, and it is why he uses it in almost every fight. On a side note, if you pay close attention to the manga, you will see that Ichigo remained in his Bankai state for over 100 chapters, even though it was only a few rough hours in the story's time.