Analyzing the chart from all three lagnas, the Ascendant, Moon and Sun, is important because it will reveal repeating patterns in the chart quickly.
For instance, in this chart of the teacher who's chart we've discussed on 12/13/2005 and 12/16/2005, look how Jupiter is strong, being exalted in the sign of Cancer, in the 4th house from the ascendant. This forms a Hamsa Mahapurusha Yoga (Jupiter in its own or exalted sign on an angle), thereby increasing the strength of Jupiter. This is a clue that this person could be a teacher. When you look further you'll see that Jupiter aspects the 10th house and the 10th lord, Saturn, reinforcing this pattern. Jupiter also mutually aspects the Sun and Mercury, two of the significators of the 10th house of career that we discussed yesterday. Again this reinforces the same pattern of teaching as a profession.
This becomes further reinforced from the alternate ascendants, the Moon and the Sun. From both of these positions Jupiter again is in a Hamsa Mahapurusha Yoga, which dramatically reinforces the strength of Jupiter, and Jupiter's significations like teaching. From the Moon, Jupiter is in the 10th house, and from the Sun, Jupiter is in the 7th house, which is the 10th from the 10th house, or a secondary house of career.