I read in a book, dignities and duties of priesthood. Interior mortification is very effect and desired by Christ the most, compared to exterior mortification.
One of my favorite books of all-time.
Alongside the Apophthegmata, it made me a traditionalist by inspiring me to seek out priests who lived the way St. Alphonsus said they should in that book.
Regarding the superiority of interior mortification, I have no doubt (breaking willfulness instead of skin, etc).
Still, if so many saints and religious orders use these things, there must be a place for them, for some people, subject to spiritual direction, of course.