The full version of Butler's The Lives of the Fathers, Martyrs, and Other Principal Saints is available at the Internet Archive and in a conveniently arranged online edition at Bartleby's Great Books Online. The 1894 Benzinger Brothers edition is very much abridged but is useful for short daily reflections on the lives of the saints. It can be found at the Sacred Texts website and put onto your mobile device as part of the excellent iPieta app.
I often use iPieta for various things and yesterday evening, in preparation for the various relevant spiritual and liturgical occurrences of today, I read the abridged entry for St Catherine of Siena. The abridged version adds short reflections for each day, probably written by the editor John Gilmary Shea. For St Catherine of Siena, it reads:
The seraphic St. Catherine willingly sacrificed the delights of contemplation to labor for the Church and the Apostolic See. How deeply do the troubles of the Church and the consequent loss of souls afflict us? How often do we pray for the Church and the Pope?As things are at the moment, I think every single day would be about right.
Incidentally, when you consider all that St Catherine accomplished during her life, it is humbling to recall that she died at the age of thirty-three.