Kevigen of Alexandria | A Catholic Gamer's Guide to Min-Maxing Your Prayer Life: the St Andrew Novena & St Gertrude Chaplet @Kevigen | Uploaded 9 months ago | Updated 9 minutes ago
Sources:

Catholic Chapel in Cork, Ireland, which reports the claim that the St Gertrude Prayer will release 1,000 souls from purgatory per recitation:
http://midletonparish.ie/prayer-of-st-gertrude-for-all-the-holy-souls-in-purgatory-2/#:~:text=Eternal%20Father%2C%20I%20offer%20Thee,Amen.

"Dramatically Increase the Number of Souls you Release from Purgatory" by Uniquely Mary:
youtube.com/watch?v=OtDFCa2Ba2Y&ab_channel=UniquelyMary

How to pray the St Gertrude Chaplet, from Catholic Crusade:
thecatholiccrusade.com/chaplet-of-saint-gertrude.html

My excel file with the St Gertrude Prayer Math:
docs.google.com/spreadsheets/d/1PqKApph60ENY8TkpsI7Z4n_DUZinau1E1U-ZpMdjptU/edit?usp=sharing

St Andrew Christmas Novena at Hallow:
hallow.com/blog/how-to-pray-the-st-andrew-christmas-novena

St Andrew Christmas Novena at Ascension Press:
ascensionpress.com/pages/st-andrews-christmas-novena

Blog (of questionable reliability) which says that the St Andrew Novena is "over 100 years old":
blog.ecclesiasticalsewing.com/2019/11/30/the-saint-andrew-christmas-novena-prayer

Chapters:

0:00 Introduction to Prayer-Maxxing
0:57 St Gertrude Prayer and Chaplet
4:09 Empty Purgatory Speed Run
9:31 Historicity and Other Problems
12:05 St Andrew Prayer and Novena
18:08 Conclusion