Well, this should be a relatively easy matter. Given that saying the Prayer of St. Gertrude the Great releases 1000 souls from purgatory each time it is said (http://www.catholicspot.com/purgatory.htm), and assuming a cumulative world population of 106,456,367,669 (http://www.prb.org/Content/ContentGroups/PTarticle/0ct-Dec02/How_Many_People_Have_Ever_Lived_on_Earth_.htm), and with a current world population of Catholics of 1 billion, only 1 out of ten Catholics would have to say the prayer once to empty out the place (even assuming everyone that ever lived is in purgatory- obviously not the case).
Alternatively, we could take Jesus at his Word when he said "It is finished".
Good Luck getting us to do that!
41 Then they all blessed the just judgment of the Lord, who had discovered the things that were hidden.
42 And so betaking themselves to prayers, they besought him, that the sin which had been committed might be forgotten. But the most valiant Judas exhorted the people to keep themselves from sin, forasmuch as they saw before their eyes what had happened, because of the sins of those that were slain.
43 And making a gathering, he sent twelve thousand drachms of silver to Jerusalem for sacrifice to be offered for the sins of the dead, thinking well and religiously concerning the resurrection.
44 (For if he had not hoped that they that were slain should rise again, it would have seemed superfluous and vain to pray for the dead,)
45 And because he considered that they who had fallen asleep with godliness, had great grace laid up for them.
46 It is therefore a holy and wholesome thought to pray for the dead, that they may be loosed from sins.
I would be happy to pray the prayers, but your links don't work.:)
A short story by me.
2 1/2 years ago I found my long lost cousin and his family after 40 years. He died within the year and was burried in St Gertrude's Cemetery in New Jersey.
I believe it was the will of God for me to see him in his last year and pray for his soul until my death.
I say 10 prayers on the Web site everyday plus the Rosary for the souls in Purgatory. I kow the ones I pray for will be praying for me in heaven when they arrive.