Saturn is Yogakarka in Libra and Taurus, who signs owned by Venus. Saturn in Mooltrikona sign means that it is in Aquarius. Assuming that Saturn is unafflicted then Saturn will give best results during its Mahadasha and also during the antardasha. Saturn will also give good results during the antardasha of Saturn and Mahadasha of friendly planet.
Actually for Libra or Tula lagan Saturn is the yogakarka planet. In case there is no major affliction on Saturn in the natives chart, the Sade Satti is not all that bad. Having said that a lot will also depend upon transit that goes along as you know 7 1/2 years of Shani Sade Satti cannot be measured in one way. Presently as you know Saturn is in Scorpio the sign ruled by Mars. Where is is not likely to bring very good results. However Anuradha the Nakshatra of Saturn is also in Scorpio from 3’20” to 16′ 40 ”. When Saturn will be in its own Nakshatra it will be more powerful.
I have some articles of Shani Sade Satti on AstrologyMag.com , you may refer those for more details.