He was pretty clear about it in his first post. He didn't specify a focal length range, but said that he needs some basic versatility: landscapes, portraits, and video all interest him. Fair enough. Lots of people start out with those basic criteria, and that's why lenses like the 24-105 exist.
But my point really was that he already has a lens, and if most of his videos and shots are, for example, shot in the 18-28mm range of that lens, then a 24-xx lens probably isn't a great option.
And if, for example, he is being limited all the time by shutter speeds too slow to handhold, then a 24-70 or 17-55 f/2.8 lens might not do the trick, and he might need a couple of primes instead.
As an example, the 24-105 f/4 certainly wouldn't add much hand-holdability compared to the 18-55 IS "kit" lens -- camera shake would still be the main problem.
And as another example, the 24-70/2.8 will probably be less hand-holdable (heavier, no IS) than the 18-55 IS kit lens, so he could end up with more blurry photos despite having a lens that's 10x more expensive.