There are typically 4-8 prayers of the faithful. The General Instruction of the Roman Missal (GIRM) does not give strict rules on the exact number, but states: “As a rule, not more than four or five intentions should be added to the series composed for the celebration.”
So while the GIRM recommends 4-5 intercessions as a standard guideline, it allows for some flexibility with the number. Many celebrations will include somewhere between 4-8 Prayers of the Faithful.
Having a small set of 4-8 intercessions allows the Prayers of the Faithful to touch on a variety of important areas of need – the Church, civil society, the oppressed, and the world at large. At the same time, keeping the number relatively contained helps maintain the solemnity and prayerful engagement of this part of the liturgy.
Ultimately, there is no definitive legislation on an absolute number. The GIRM provides a general guideline of 4-5, while allowing the local celebration to determine what number of Prayers best serves the needs of the congregation and situation. As long as the prayers remain clear, comprehensive yet concise, whether 4, 5, 6, 7 or 8 – they can fulfill their role of activating the baptismal priesthood on behalf of all people.