It is part of the immemorial tradition of Catholic piety that, after consecrating Friday to commemorate the Passion of Jesus Christ and to honour his Sacred Heart, it is totally natural to consecrate Saturday to his Blessed Mother.
Apparitions of Jesus in Paray-le-Monial
Furthermore, Pontevedra's request seems to be the happy result of a movement of devotion, spontaneous at first, then encouraged and codified by the Sovereign Pontiffs.
In 1889, Leo XIII granted indulgences to the faithful who would consecrate, through special devotions, fifteen Saturdays in honour of the Virgin of the Rosary.
On July 1, 1905, Saint Pius X approved the practice of the first twelve Saturdays of the month in honour of the Immaculate Conception. Finally, on June 13, 1912, he granted, for the first Saturday of each month, a plenary indulgence applicable to the souls in Purgatory. The conditions were very similar to those of the Blessed Virgin in Pontevedra: confession, communion, prayers for the intentions of the Sovereign Pontiff and pious practices “with the intention of making reparation in honour of the Immaculate Virgin.”
Saturday is a day of transition between the painful day of Friday and the glorious day of Sunday. Our Lady acts as a bridge to intercede for us, to lead us to Jesus. We ask her to intercede for us and we ask her to teach us to be like her: humble, patient, kind, pure, simple, docile to the will of Our Lord.