First, I think a few things are worth noting:
- most discussion about post-awakening cultivation takes place in Song-dynasty literature; many Tang dynasty Zen texts emphasize sudden awakening and suggest that it is totally realized in an instant
- Shenxiu vs. Shenhui was a more recent memory in the Tang; perhaps this is a factor in why Tang dynasty texts are so subitist
- it's only in the Song dynasty that we start getting a lot of reliable records of teachings, anyway
- I don't think it makes any sense to attribute this difference to a mere difference in teaching styles, considering that it relates to how kensho is experienced, which is fundamental to Zen
- I personally take the view that the Tang writings are less reliable, given that they are not written in the teacher's own hands, and also more incomplete, given how much smaller Tang dynasty lu are compared to Song dynasty ones.
- most Zen literature is still untranslated, so it is quite possible that there is much more discussion of post-awakening cultivation in Zen texts than English speakers know
Daoxin:
"Those who hear should practice: don't be doubtful and confused. It is like a person learning archery. At first he shoots at large targets. By and by he can hit smaller and smaller ones. Then he can hit a single feather, then hit it and smash it into a hundred pieces, then hit one of the hundredths. Then he can shoot the arrow before with the arrow after, and hit the notch, so the arrows line up one after another and he does not let any arrows fall. This is a metaphor for practicing the Path, concentrating the mind from thought-instant to thought-instant, going on continuously from mind-moment to mind-moment without any interruptions, so that correct mindfulness is not broken and appears before you." (from Anxin Famen)
Hongren (?):
"This true mind is natural and does not come from outside. It is not confined to cultivation in past, present, or future. The dearest and most intimate thing there could be is to preserve the mind yourself. If you know the mind, you will reach transcendence by preserving it. If you are confused about the mind and ignore it, you will fall into miserable states. Thus we know that the Buddhas of all times consider the inherent mind to be the basic teacher. Therefore a treatise says, "Preserve the mind with perfect clarity so that errant thoughts do not arise, and this is birthlessness." (Treatise on the Supreme Vehicle)
"The Mind King Scripture says that true thusness, the Buddha-nature, is submerged in the ocean of cognition, perception, and sense, bobbing up and down in birth and death, unable to escape. Effort should be made to preserve the basic true mind, so that arbitrary thoughts do not arise, egoistic and possessive attitudes vanish, and you spontaneously realize equality and unity with the Buddhas." (ibid.)
"Enlightenment is realized by knowing mind; confusion happens because of losing touch with nature. If conditions meet, they meet; no fixed statement can be made. Just trust in the truth and preserve your inherently basic mind." (ibid.)
"Once we know that the Buddha-nature in all beings is as pure as the sun behind the clouds, if we just preserve the basic true mind with perfect clarity, the clouds of errant thoughts will come to an end, and the sun of insight will emerge; what is the need or so much more study of knowledge of the pains of birth and death, of all sorts of doctrines and principles, and of the affairs of past, present, and future? It is like wiping the dust off a mirror; the clarity appears spontaneously when the dust is all gone." (ibid.)
Huineng
"If in all places you do not dwell on appearances, do not conceive aversion or attraction to any of those appearances, and have no grasping or rejection, do not think of such things as benefit, fulfillment, or destruction, and you are at peace, calm, open, aloof, this is called absorption in oneness. If in all places whether walking, standing, sitting, or lying down, your pure unified direct mind does not move from the site of enlightenment, truly making a pure land, this is called absorption in one practice. If people are equipped with these two absorptions, it is like the earth having seeds, able to store, develop, and perfect their fruits. Unity and unified practice too are like this." (Treasury of the True Eye of Teaching, vol. 2)
Longtan:
"At these words, Lung-t'an's mind was opened and he understood. Then he asked how to preserve this insight. The master said, “Give rein to your Nature in its transcendental roamings. Act according to the exigencies of circumstances in perfect freedom and without any attachment. Just follow the dictates of your ordinary mind and heart. Aside from that, there is no ‘holy' insight.” (from Terebess)
Yuanwu:
"Your only fear should be that your own correct eye is not yet perfectly clear. This will cause you to fall into duality, and then you will lose touch with reality." (Zen Letters, p.56)
"If you can make it continuous and unbroken, how will it be any different than when you were in the monastery being guided by the abbot and doing your meditation work? If you turn your back on it at all, and there is some break in the continuity, then you will lose contact." (Zen Letters, p.61)
"When this is closely continuous without any leaks, this is what is called standing like a wall miles high, lofty and steep." (Zen Letters, p.65)
"When you are in this state of great concentration, isnt this inconceivable great liberation? Just let it continue for a long time without interruption." (Zen Letters, p.72)
"Just keep boring in -- you must penetrate through completely. Haven't you seen Muzhou's saying? 'If you haven't gained entry, you must gain entry. Once you have gained entry, don't turn your back on your old teacher.' When you manage to work sincerely and preserve your wholeness for a long time, and you go through a tremendous process of smelting and forging and refining and polishing in the furnace of a true teacher, you grow nearer and more familiar day by day, and your state becomes secure and continuous. Keep working like this, maintaining your focus for a long time still, to make your realization of enlightenment unbroken from beginning to end." (Zen Letters, p.74)
You must continue this way without interruption forever -- this is the best." (Zen Letters, p.89)
"It is just a matter of never letting there be even a moment's interruption in your awareness of your real nature." (Zen Letters, p.96)
"When you reach the point where feelings are ended, views are gone, and your mind is clean and naked, you open up to Zen realization. After that it is also necessary to develop consistency, keeping the mind pure and free from adulteration at all times. If there is the slightest fluctuation, there is no hope of transcending the world." (from Zen Essence)
Dahui:
"Often people of sharp faculties and superior intellect get it without expending a lot of effort. They subsequently produce easy-going thooughts and do not engage in practice. In any case, they are snatched away by sense objects right in front of them and cannot act as a master subject. Days and months pass, and they wander about without coming back. Their Dao power cannot win out over the power of karma, and the Evil One gets his opportunity..." (from Zongmi on Chan, p.60)
Muso Soseki:
"Since ancient times it has been said that ascertainment of truth is relatively easy compared with the difficulty of preserving truth. Preservation of truth is the work of maturation." (from Dream Conversations on Buddhism and Zen)
Bankei:
"My only reason for speaking to people like this is because I want to make everyone know about the marvelously illuminating clarity of the unborn Buddha-mind. When you've confirmed it for yourself, you're the Buddha-mind from then on. No different from Shakamuni himself. The Buddha-body is yours once and for all, for endless ages, and you won't ever fall into the evil ways again.
"And yet, should you grasp the unborn Buddha-mind at this meeting and then return home and let yourself be upset over something you see or hear, even if it's a trifling thing, that little bit of anger will make the unborn mind, to which you were just enlightened, change into the way of the fighting spirits or hungry ghosts, increasing the great evil of the life you lived prior to hearing about the Unborn by hundreds of millions of times and causing you to pass endlessly through the wheel of existence." (The Unborn, p.95)
Shido Bunan:
"If you can really get to see your fundamental mind, you must treat it as though you were raising an infant. Walking, standing, sitting, lying down, illuminate everything everywhere with awareness, not letting him be dirtied by the seven consciousnesses. If you can keep him dear and distinct, it is like the baby's gradually growing up until he's equal to his father - calmness and wisdom dear and penetrating, your function will be equal to that of the buddhas and patriarchs. How can such a great matter be considered idle?" (from Sokushin-ki)
Torei:
"Mightily manipulating the pearl of awareness, I didn’t put it down for an instant. Sometimes getting it, sometimes losing it, I found correct mindfulness hard to keep continuous. Sorrow and apprehension clogged my chest, and I was uneasy whether sitting down, or up and about." (Undying Lamp of Zen, p.78)