Several popes confirmed that if this prayer was said 33 times on Good Friday, it would free 33 people from Purgatory. If said 50 times on a Friday, it frees five souls. If Purgatory's anything like the kids from Fatima said, you want to get your people out. Seriously.
I worship you, O Holy Cross, which was adorned with the most Holy Body of my Lord, covered and stained by his precious Blood. I worship You, my God, crucified for me. I worship you, O Holy Cross, for love of the one who was my Lord. Amen.