Here's H.H. Dudjom Rinpoche on the benefits of doing tshog on the 10th day each month:
Similarly, there are special benefits accruing to us from the observing of the monthly Pujas on each of the Tenth day great festivals in the order given above. For example, those evil spirits which cause the disease will be pacified. Our length of life, virtue and wealth will increases; and our happiness of mind, quick encourage, and brilliance of personality will likewise increase. Both human beings and non human spirit will gather under our power; our dominion and prosperity will increase; and the local deities and the guardian spirits will heed us as if they are our servants. The harm and injury caused by the Lord of Death and the eight groups of spirits will be mitigated. Our moral precepts will be completely purified and our wisdom will radiate into every area. The dangers due to unfavorable planets and stars, unlucky days, enemies and thieves will no longer threaten us; good fortune and well being will increase everywhere at home and abroad. The mischief due to earth-spirits (sa-bdag), Nagas, and fierce subterranean beings (gNyan) will likewise no longer threaten us; and the Dharma Protectors and the Guardians will accomplish those deeds with which they are charged. The damaged caused by are hindrances, enemies, and evil spirits will be ameliorated; and will gather under our power whatever we desire. Diseases which cause the body to waste away will be cleansed; bodily health and happiness of mind for ourselves as well as our friends and relatives will increase; and we will obtain whatever object we contemplate. Unlucky periods among the days, months and years, as well as ill omen generally, will be mitigated; and we will fully recover whatever dominion and good fortune we may have lost. Evil spirits, who cause diseases, such as the Bhutas and the eight groups of spirits, as well as the conditions of untimely death will likewise be pacified. We shall be freed from the ill effects of contagious magic (gtad), the disabling effects of mantras which impair the function of the intellect (sel) and which disturb our peace of mind (byad-kha), as well as elemental spirits evoked to harm us by causing disease or calamity (rbod-gtong). Indeed, our own body will become as strong as diamond. Hypocritical deeds in violation of our precepts, such as any defect or default of the three types of vows, as well as all transgressions of the samaya vows, will be cleansed; and our mind will become pure. Ultimately death and other accidental disasters will not arise, and immediately upon passing from this life we shall be reborn in the presence of the Guru Himself in the Realm of Lotus Light, Padmaprabhaksetra, (Padma od zhing). Also, from the practice of reciting the prayers in their proper order particularly at the time of performing Puja, we shall become as one who possesses infinite benefits; our accumulated merit shall be inexhaustible.
According to the Lama Sang-du (bLa ma gSang-dus): “On the Tenth Day of the monkey month of the monkey year: And on all the Tenth Days of the other months, my manifestations will emanate throughout Jumbudvipa in particular; and I shall bestow siddhis both ordinary and supreme. As for those who perform saddhana of the Guru throughout their entire life. If they persist in this, then at the time of passing from this present life, they will be absorbed into my own heart centre.” According to the Treasure tradition (gter- lung) of Ratna Lingpa: “When who remember me, as if carrying a pebble in their packet as a reminder, They and I shall indeed be inseparable To My sons, my disciplines, the king and ministers of Tibet. On the Tenth Day of each month, I myself will appear: this I promise. I, Padmasambhava, would never deceive others.” According to the zhal-dam Ser-treng (Zhal-gdams gser-phreng): I, Urgyen, particularly on the Tenth Day which is the Great Festival, Will come to the snowy land of Tibet, Riding upon the rays of sun and moon, The rainbow, the mists or rain; And shall remove all obstacles impeding, my devoted disciples. Upon each I shall bestow the four consecrations which they desire. This is my promise and Padma would never deceive anyone. If one who is devoted to me always observes the puja on the Tenth Day. By virtue of practicing the saddhana according to my instructions, He will realize the well being of the kingdom.”
He confirmed these adamantine verses, which surely speak the truth, many times and not one time only. He would never deceive those disciples appearing in later times who believe in His promise with all their heart. With ever increasing effort may they spread widely these festivals which are always productive of benefits and happiness in one’s present life and in all future life. May this festival of benefit and joy be always observed everywhere, together with the Dharma in the presence of those who desire liberation. Similarly, may these glad tidings be displayed like a beautiful young maiden attractively be jeweled and graced with well-explained excellent meanings for every word.
(Translated by John Reynolds, Vajranatha)