This prayer along with The Prayer of Repentance (Salah al-Tawba) are two sunnah prayers that offer mindfulness to those committed to this spiritual path and its work.
Salah Al-Haja is a prayer for something of worldly needs. It is an important sunnah.
In the Kitāb Al-Adkar by Imām Nawawī states two different types of this prayer with two different Duʿāʾ.