The major problem is a misunderstanding of essential dignities. The strongest of elemental dignities stipulates other cards of the same suit. However, most people don't read Mathers very closely (if at all), where he says that when cards are of the same suits/elements, they are “very strong for either good or evil, according to their nature.” People just don't get the "or evil" part of this.
For instance, what happens, according to astrological principles, when the 2 of Pentacles appears with the 9 of Pentacles (Venus in Virgo)? Both Beneficients are in their "Fall." Yes, we have gain and material increase through, or with, harmonious change. There's a ton of "luck" here but probably no development of character as the money wasn't made through one's own efforts. Rather it suggests that money or resources would be spent readily and frivolously with little being produced. I could also imagine owning fancy, expensive possessions that, when damaged, you readily throw away and buy another, rather than fix, as they have no inherent value to you. The combination suggests it's a strong factor, and the weakness of the decanates suggest there's some kind of danger. It could be like winning the lottery but ending up with nothing to show for it once the period of "gain" is past.
Added: The Venus in Virgo decanate is usually seen as leaning toward excessive savings and avarice: "penuriousness." From this pov, when combined with Jupiter in Capricorn, it could go to the opposite pole like those with inherited wealth who are tight-pursed out of fear that they might wake up poor one day--but, again, because they know that they themselves have produced nothing of substance.
Mary