One custom, associated with the Tridentine Mass and the New Liturgical Movement or Reform of the Reform movement, is for lay people and sacred ministers alike (including sacristants and those employed by the church) to genuflect each time they pass in front of the tabernacle. Another custom is for a single genuflection upon entering and exiting the sanctuary to stand in for these multiple genuflections.
According to the Third Typical Edition of the General Instruction of the Roman Missal, the sacred ministers are to genuflect to the tabernacle upon entering and departing the sanctuary (except if prevented because carrying the cross or candles in a procession), and to make a profound bow when crossing in front of the altar at other times. Outside of the celebration of Mass, the normal custom for genuflections in the sanctuary would prevail.
It is was formerly required to perform a double genuflection (on both knees) before the Blessed Sacrament exposed in a Monstrance, although the current rite for Exposition does not specify which type of genuflection and the opinions of rubricians vary on whether a single or double genuflection should be made.
On Good Friday and Holy Saturday Roman Catholic Churches do not contain the Blessed Sacrament. However, according to liturgical law, the faithful should genuflect to the cross on these days once it has been revealed in the Good Friday service. The Blessed Sacrament is reserved in the Altar of Repose in those days; customarily when passing in front of that Altar, the faithful kneel on both knees and make a profound bow in that position . In churches of the Anglican Communion, it is customary on Good Friday to venerate a large cross or crucifix, and the devotional act may include a simple or double genuflection.
In the Maronite Catholic Church, there is an evocative ceremony of genuflection for the feast of Pentecost. The congregation genuflects first on the left knee to God the Father, then on the right knee to God the Son, and finally on both knees to God the Holy Spirit.
Members of the Eastern Catholic Churches generally make a profound bow in the same situations where a Latin rite Catholic would genuflect. In the Roman Catholic and Anglican Communions, a profound bow is an acceptable substitute if one is physically unable to genuflect. Due to Latinisation, however, many still kneel or genuflect in private prayer. It is considered extremely rude to enter a Greek Catholic church and genuflect rather than making a metasis (deep bow paired with crossing oneself).
The times for making each of these reverences are fixed by tradition, though they may differ from one ethnic tradition to another, and are intended to help to unify the congregation in their active participation in the service.