What is the importance or significance to which house a planet is "Ruling" in interpreting a transit or aspect?

The more influences you know about a planet or a house the more you understand it. You have to look at the chart to see where those particular houses are, not just the traditional rulers of the houses. So if you want to know about your money situation, look to YOUR 2nd house, if Scorpio is there then to describe it in more detail look for where Pluto is. Scorpio will tell you that you must be careful about unscrupulous dealings where money is concerned. Then look at Pluto to see where those dealings occur or a description of who it is. If its in the 7th then look to the partner with more caution if financial schemes are suggested. So the house that the planet is in is the first place to look and then the house it rules should be looked at for more detail. Does that make sense? If not ask again.