The Light of Wisdom, the Conclusion, presents detailed explanations of the activities of a Vajra Master and Buddhist practices to clear away hindrances on the path and enhance realization. The book is a combination of three texts:
The root text, The Gradual Path of the Wisdom Essence is oral instructions of Padmasambhava, recorded by his chief female disciple, Yeshe Tsogyal. Padmasambhava established the Buddhist doctrine in Tibet during the eight century. He concealed teachings in the form of hidden treasures, to be revealed at an appropriate time in the future. The Light of Wisdom by Jamgön Kongtrül, one of the most prominent Buddhist masters of nineteenth-century Tibet, is an extensive commentary on this sacred scripture. Entering the Path of Wisdom consists of annotations on the commentary by Jamyang Drakpa, a student of Jamgön Kongtrül, dictated to Jokyab Rinpoche.

The root text of Lamrim Yeshe Nyingpo, a terma revealed by the great treasure-finder Chokgyur Lingpa, and its commentary by Kongtrül Rinpoche, the great translator in person, form together a complete scripture that embodies all the tantras, statements and instructions of the Nyingma School of the early translations, which is most rare to find in the past, present, or future. ...I find it important that all Dharma practitioners study and reflect upon this book.
? Kyabje Dilgo Khyentse Rinpoche

It is correct that it will be quite difficult to practice the entire Gradual Path of the Wisdom Essence, so you should use what is directly appropriate for your training. It is never said that you should practice an entire root text as Light of Wisdom contains the complete path for different kinds of individuals, both of Hinayana, Mahayana and Vajrayana. But since its title is the Wisdom Essence, it means that its ultimate practice is Dzogchen.
? Kyabje Tulku Urgyen Rinpoche