I wouldn't use dignity for that purpose. I would just focus on the combination of a Mars message with a Taurus message, or the combination of a Jupiter message with a Gemini message.
I would pay attention to house placement, because that modifies the message (Jupiter in Gemini in the tenth will be saying something about the career/public reputation area of a person's life, while the same placement in the fifth would be saying more about creative pursuits, hobbies, or children, for example). And any planet right on an angle will be amplified. But all the nuances of dignity aren't relevant here.
If someone's telling you that and you have their birth chart, look at the pattern. Are the planets spread out around the chart? Bunched together?
Interested in too many things usually goes along with having a splash or splay or sometimes even a locomotive chart: planets spread all around. This is someone who's wired to have multiple areas of focus and needs to keep their fingers in multiple pies. Just focusing on one thing won't do for them. They might have to prioritize what to focus on at a given moment, but they also need to keep room for their other interests in their life. Telling that person to just pick one thing is poison to them.
That goes with the midlife transits. Between your late thirties and your mid forties, you get (everyone gets) Saturn square its natal position, then Neptune square, then Uranus opposition, then Saturn opposition. Uranus opposition in particular is a break free, blow it all up energy, but Neptune and Saturn have their roles, too. Neptune dissolves. Neptune reminds you what your dreams are. Saturn's hard angles make you take a long, hard look at what's important. Is this what I've worked for? Is this what I should be working for?