The scripture readings and prayers of the Catholic Mass and the Liturgy of the Hours influenced organists to play certain chants one or more times a year after year for centuries. These simply grew into their fingers, muscle memory. And became part of history.

Veni Creator is one of those chants.

Mark Martin in his Thesaurus Precum Latinarum writes:

One of the most widely used hymns in the Church, Veni, Creator Spiritus, is attributed to Rabanus Maurus (776-856). It is used at Vespers, Pentecost, Dedication of a Church, Confirmation, and Holy Orders and whenever the Holy Spirit is solemnly invoked. A partial indulgence is granted to the faithful who recite it. A plenary indulgence is granted if it is recited on January 1st or on the feast of Pentecost.