Re: 5 or 6+ planets in the same sign?
Yes, notably my husband's daughter from his first marriage. I think such people have the capacity for tremendous focus, but a lot depends upon the sign and house; as well as any aspects to them Someone with a huge Aquarius concentration, for example, could be a dedicated scientist or humanitarian; someone with a lot of Taurus in the 4th house might be great as a real estate broker. An afflicted Virgo concentration, on the other hand, could create a lifelong critic for whom nothing is ever good enough; while a Capricorn stellium in the 12th could suggest a real hermit.
Whatever it is, a person with a big stellium in one sign (and probably also in one or two houses) is "majoring" in that sign and houses. And they must do that to be authentic. By the same token, because they are not so oriented towards other modes of experiences and domains of activity, they may not be interested in them or patient with what they represent. Because everything in their lives will revert back to the stellium.