When Jupiter (Guru or Brihaspati) occupies his own house and is also in the aspect of trine to lagna, it results in Sasaka Yoga. The person with this yoga will be blessed with great wealth and all comforts of life.
This is one of the Dhana Yogas. Going by the accepted principles of Indian astrology, Jupiter has to be well placed for any Dhana Yoga in general, because this planet is the karaka (significator) for wealth.
In this yoga, by being in its own house, Jupiter is already powerful. This assures good wealth. The other conditions are dependent upon the planet from which it is receiving aspect.
Jupiter in its own house and aspected by a planet like Venus or Mercury may not be so favorable to the means employed in amassing wealth. In fact, this yoga, like any other yoga, should be interpreted after properly assessing the strength of the yoga karaka planets.
Even in the preliminary conditions of this yoga, Jupiter of Pisces will bestow greater effect that then Jupiter of Sagittarius, though in each case Jupiter is the owner of the sign.
Bibliography
Astrology For You (1985) Shakuntala Devi – Orient Paper Books
Encyclopedia of Hinduism Volume IX page 300 - 1