Anicca is not about the complexity of all the causes and conditions that form kammic effects or consequences, ( vipāka). Rather,it is one of three characteristics of all conditional phenomena: anicca, dukkha, annatā.
Anicca means impermanence, inconstancy; and in a more interpretive sense can point to the unreliability of any conditioned phenomena to be a “permanent” refuge from dukkha, (let’s say suffering, pain). Quite the opposite – because of inconstancy, all conditioned things are dukkha.
In SN 36.11 the Buddha says, ‘yaṁ kiñci vedayitaṁ, taṁ dukkhasmin’ti. ‘Suffering includes whatever is felt.’ When I said this I was referring to the impermanence of conditions, to the fact that conditions are liable to end…"
Kamma fundamentally is cetana, volition/intention. “Cetanā ahaṁ bhikkhave kammaṁ vadāmi”, “It is volition or intention, monks, that I call kamma,” (AN 6.63).
From this, kusala and akusala point to intentions/actions that lead the mind towards dispassion (viraga), the ending of craving (tanha khaya), and liberation from all dukkha, (vimutti).
The N8FP lays out the aspects of the Path to be practiced as in SN56.11 and many other suttas.
Specifically, Right Effort is about cultivating wholesome states and letting go of unwholesome ones.
Why? Because although they are conditional, wholesome states lead to less craving, grasping, and to samadhi and wisdom. And the opposite is true for unwholesome states.
So it’s not about having to know all the conditions that combine to manifest a particular physical or mental state or predicting exactly what the next experience will be.
Rather, it’s about skillfully using conditions and intentions in a way that leads to beneficial kammic effects which, in turn, are conducive to further wholesome states in a manner that leads to fully letting go and untimately nibbāna, the ending of all conditions and the ending of all dukkha.