The practice was never to cover statues and crosses for all of Lent, just the last two weeks of Lent, a time known traditionally known as Passiontide. There were several liturgical features, including the omission of the Gloria Patri and the psalm Judica me in the prayers at the foot of the altar. Though the Passiontide portion of Lent was mainly relegated to Holy Week in the 1970 missal, the permission to veil beginning on the 5th Sunday of Lent (formerly known as Passion Sunday) remains in the current missal, as has been pointed out here.