The mahima of Durga naam can't even be told by Shiv in tantras. He says thus,
दुर्गानाम जपो यस्य किं तस्य कथयामि ते।
अहम् पंचैननह् कांते तज्जपादेवसुव्रते।।
Oh, devi how could I narate he glory of the name 'Durga'? It is of the recitation of the Durga Naam that I am called panchanan.
Imagine, Shiv himself says that it is by chanting of Durganaam that he is called Panchavaktra(The one with 5 faces). Now the name Panchanana is highlighting in itself. It is from these 5 faces that Shiv established the 5 Anmayas and gave Tantra, Agamas, Shastras etc. Thus Mahadev credits it all to durga naam, and it's japa. Indirectly he point out that, it's by Durga naam that he created so many scriptures.
Mahadev says in other tantra that,
श्रृणुदेवी वरारोहे ममैव निश्चितं वचह्।
विना दुर्गा परिज्ञानाद विफलं पूजनं जपह्।।
दुर्गा हि परमो मंत्र दुर्गा हि परमोजपह्।
दुर्गा हि परमं तीर्थम दुर्गा हि परमह् क्रिया।।
दुर्गा हि परमा भक्तीदुर्गा मूर्तिमहितले
बुद्धिनिद्रक्षुधा छाया शक्तिस्तृष्णा तथा क्षमा।
Oh boon giver Devi! Listen to my infallible words. Without the knowledge of Durga, one's pooja and Japa bear no fruits. Durga is supreme Mantra, Durga is supreme Japa. Durga is the supreme Tirth and the supreme Kriya. She is also the nature of supreme Bhakti on the nature of highest Mukti on this earth. Intellect, sleep, hungry, veil, energy, forgiveness,Mercy,certainty, peace, prosperity and memory. All of them are verily Durga not different from her that's why recite always the name Durga.
Thus fruis of recitations are as follows-
धनी पुत्री तथान्यानि चिरंजीवी भवेभ्दुवि।
प्रत्यहं यो जपेद भक्तया शतम् अष्टोत्तरं शुचिह्।।
One who recites the name of Durga 108 times everyday, is blessed with prosperity offspring wisdom and longevity.
दुर्गा नाम जापात पापं सर्व्वय्याति हि ततक्षणात।
वेदास्वागमतंत्रेषु पुराणेषु सुनिश्चिम।।
दुर्गा नाम समाख्यातंा चतुर्वेदविदंा मतम्
By recitation of the name Durga all sins get destroyed it is ascertained by Vedas, Agam, Tantra and Puranas, verily Durga Naam is embodiment of four Vedas.
दुर्गा दुर्गेति दुर्गेति दुर्गानाम पर मनुम् । यो भजेत् सततं चण्डि! जीवन्मुक्तः स मानवः ॥ महोत्पाते महारोगे महाविपदि सङ्कटे । महादुःखे महाशेके महाभये समुत्थिते ॥ यः सदा संस्मरेद् दुर्गा यो जपेत् परमं मनुम् । स जीवलोके देवेशि ! नीलकण्ठत्वमाप्नुयात् ।।
Śrī Śiva: Durga, Durga Durga- This Durga name is the best mantra. Hey Chandi! the human who always worships this mantra, that human life gets liberated. In great distress, in great disease, in great calamity, in great sorrow, in the presence of great fear, one who always remembers Durga, who chants the best of Durga's mantra, O Goddess! In the world of mortal life, he gets benefited with Neelkanthatvā.
यन्नाम संस्मरन् शम्भुः पिबन् हालाहलं परम्
विजित्य मृत्युं लोकेऽस्मिन्नाम्ना मृत्युञ्जयोऽभवत् ॥
By Remembering Durga's Name, Lord Śankarā became famous in this world by the name of Mrītyunjayā, having conquered death even after drinking the terrible Poison (Halahala).