Holist, I agree with you. I think a planet is in one sign or the other, down to the minute and second. Obviously with a rounded birth time, you might get some confusion. But the signs are so different from the neighbours.
I think the ascendant is a major factor, but the MC really deals with public image and vocation in life, which may or may not be so critical for the person. I tend to treat the DC and IC just like house cusps. Unless I'm using whole signs houses.
Usually if someone says he doesn't feel like his sun sign, he's got other stuff going on in his chart. I'd look at the house ruler of the sun's house, aspects to the sun, and planets in the house that he does feel like.
Also, many people have only the sketchiest, pop-schlock notion of what a sun sign is supposed to be like. Jupiter is normally the "feel good" planet, so it is easy to gravitate to matters of Jupiter's sign and house.
Houses are different, because house cusps will vary depending on the system used.
Air signifies mental, intellectual, ideological. Air people (of which I am one, with 5 planets in air signs) enjoy ideas for their own sake. They don't require a practical application. Air may or may not be intuitive, as water is the element of empathy and sympathy.
Where is this man's Mercury? Mercury in earth tends to be practical and applied. Mercury in fire is guided by enthusiasm and initiative. Mercury in water has an emotional overtone.
Sometimes people missing an element tend to compensate by relying on some other aspect of their charts. For example, having a lot of air and fire in my chart meant that I have only one planet in water, Mars; who is not Mr. Touchy-Feely. During the latter part of my career, I had to do a fair bit of trouble-shooting for people, often on a one-on-one basis. I recognized that I had limited ability to feel with the other person: they were hurting or angry or something, and I was intellectualizing rather than getting the gut-level core of what mattered to them. But drawing on my air nature, I tried to observe them carefully: what they said, how they acted.
It sounds like this man is drawing on some other element, which seems more like Virgo or earth, but it is hard to say without seeing the chart, notably Mercury's situation.
App Leo, I think your numerical weighting is a good place to start. As you get a better feel for horoscopes, you may find you don't use them so much.
To me, aspects are the most important part of a chart reading. So maybe Saturn is .5, but if he's in a tight orb square to a personal planet, say Mercury, negative thinking or even depression may be a key feature of the person's life. Generally the tight orbs in hard aspects are the ones that the person absolutely has to deal with. Think of it as a developmental or evolutionary pressure; whereas a grand trine allows people to coast.
Aspects and mutual reception can bump up other planets in the rating scheme.
