I know the Devil has insidious ways of tempting and going after each of us, and people’s weak spots differ, so the means used by the Devil and his minions also differs.
However, I was just reading about how St. Paul of the Cross was regularly physically attacked by demons, who tried to dissuade him from his priestly vocation or just interfere with his activities. I know there are other saints who were regularly physically attacked by demons, such as St. Padre Pio and St. Martin de Porres. But in other cases saints simply seem to have seen demons rather than getting beaten up by them, or they didn’t have any such experiences though they may have experienced doubt or despair which undoubtedly came from the Devil.
Why do demons manifest in such a physical way to some saints and not to others? All saints are very holy, so I am skeptical that it’s because Saint X was so much holier than Saint Y.
Scholarly/ theological support for your answer would be helpful.