[murphE]

Did nobody think to apply the SSPX approach in all that time?

It is not the SSPX approach, they are just imitating the saints, like St Vincent Ferrer. He did just what Fr. Schmidberger is saying to do and St. Vincent Ferrer was very successful.

"...his first biographer, estimates the number of Jews converted at 25,000."

Catholic Encyclopedia

It's amusing that imitating the saints is now considered "ultra" traditional.

[marshmallow]

I'd be a little careful about equating the SSPX approach with St. Vincent Ferrer's. Telling people up front that their religion is empty and false usually has a counterproductive effect. Think how you react when posters on this board say that Catholicism has it all wrong.

I think the SSPX approach is a little more like the traditional Spanish approach to the Jews, pre-St. Vincent Ferrer;

"At different times in Spanish history strenuous attempts had been made to convert the Jewish people, baptism or spoliation being the alternatives offered to them."

Conversion is usually instigated by the realization that the faith being proposed possesses Divine truth and that in turn is usually inspired by personal witness.