It is my impression that the instructions are mostly seen as methods for development of;
- Factors of Enlightenment
The perceptions include and are not limited to;
- Perception of Mindfulness of Breathing
- Perception of Inconstancy
- Perception of Not-Self
- Perception of Danger
- Perception of Compassion
- Perception of Altruistic Joy
- Perception of Unattractiveness
- Perception of Mindfulness of Death
- Perception of Old Age
- Perception of Sympathy
- Perception of Abandoning
- Perception of Drawbacks
It is a fact that all these methods are referred to as development of perceptions, this is seen in https://www.accesstoinsight.org/tipitaka/an/an10/an10.060.than.html
Apart from the unusual use of the term "perception" one can see that each of these developments sheds light on the overall development of faculties(discernment, concentration, effort, mindfulness and conviction).
As for development of the factors of enlightenment their development is explained as timely and untimely, wherein it is explained that there is a proper and unproper time to develop the enlightenment factor of concentration... of joy... of tranquility... of effort ... of equanimity.
IE when one is restless it is wrong time to develop the factor of energy and a good time to develop the factor of concentration.
The way to develop the various factors is also explained in variety and detail, ie;
- There is a development of concentration which leads to Pleasant
Abiding in the here & now
- There is a development of concentration which leads to Knowledge and Vision
- There is a development of concentration which leads to Persistent Mindfulness
- There is a development of concentration which leads to leads to the ending of the effluents
Returning to the development of perceptions, as it seems to me, they are associated with the various factors of enlightenment and faculties and have their own expected results and timely application, here are examples;
If the monk intent on heightened mind were to attend solely to the theme of concentration, it is possible that his mind would tend to laziness. If he were to attend solely to the theme of uplifted energy, it is possible that his mind would tend to restlessness. If he were to attend solely to the theme of equanimity, it is possible that his mind would not be rightly concentrated for the ending of the fermentations.
Bhikkhus, to the bhikkhu practicing the perception of lacking a self in unpleasantness and abiding much in it, whatever distinctions arise as superior, inferior or equal in the sixfold conscious body and all external signs, are appeased and well released.
Bhikkhus, to the bhikkhu practicing the perception of impermanence and abiding much in it, gain, honour and fame keeps away, it shrinks and rolls away. The mind stretches out and gets established in equanimity or loathing
The comprehensive breakdown of all the perceptions is too much to get into in a post here but it is all encompassing training for all situations for the proper attending to reality as it occurs.
IE consider the Perception of Abandoning;
"And what is the perception of abandoning? There is the case where a monk doesn't acquiesce to an arisen thought of sensuality. He abandons it, dispels it, & wipes it out of existence. He doesn't acquiesce to an arisen thought of ill-will. He abandons it, dispels it, & wipes it out of existence. He doesn't acquiesce to an arisen thought of harmfulness. He abandons it, dispels it, & wipes it out of existence. He doesn't acquiesce to arisen evil, unskillful mental qualities. He abandons them, dispels them, & wipes them out of existence. This is called the perception of abandoning.
To do this there are guides in the Sutta, in particular https://www.accesstoinsight.org/tipitaka/mn/mn.020.soma.html
wherein there are given 5 steps for mastering thoughts and crushing the unwholesome thought formations as they occur.
Therefore if one has a teacher he would ideally just tell you what to do from time to time but if one was one's own teacher relying on the Sutta one would develop wholesome qualities all of the time in as far as there is an opening and opportunity.
One would develop what is lacking and is favorable, be it to counter some unwholesome tendencies or achieving pleasure not associated with sensuality in order to achieve contentment with the holy life, one would constantly develop the good by "skillful means".