Joe -As relaxation is important in most forms of zazen and other forms of sitting, some writers on the subject of samadhi write that one can continue to drop disturbances or "distress", as you come to notice them, one after the other.
I have found this to be true. I talked before about searching out issues generating mental distress and immersing in the unpleasant associated feeling. A state can come along, when each issue can be identified and dissolved with each breath cycle i.e. if the issue is not a major. These are harder nuts to crack but IME can be worth gold
Many students report the phenomenon of of old forgotten memories and associated feelings popping up during Zazen. This is common in my practice. However, there has been occasions when a new memory would flood in and then disperse at every breath. This can go on for 20 breaths or more. It occurs naturally
No big deal but interesting just the same. It hasn't happened for some time