A helpful quote from Frank Herbert's "Dune", easily as applicable to the Wizard as to the Mentat.
"Above all else, the mentat must be a generalist, not a specialist. It is wise to have decisions of great moment monitored by generalists. Experts and specialists lead you quickly into chaos. They are a source of useless nit-picking, the ferocious quibble over a comma. The mentat-generalist, on the other hand, should bring to decision-making a healthy common sense. He must not cut himself off from the broad sweep of what is happening in this universe. He must remain capable of saying: "There's no real mystery about this at the moment. This is what we want now. It may prove wrong later, but we'll correct that when we come to it." The mentat-generalist must understand that anything which we can identify as our universe is merely part of larger phenomena. But the expert looks backward; he looks into the narrow standards of his own specialty. The generalist looks outward; he looks for living principles, knowing full well that such principles change, that they develop. It is to the characteristics of change itself that the mentat-generalist must look. There can be no permanent catalogue of such change, no handbook or manual. You must look at it with as few preconceptions as possible, asking yourself: "Now what is this thing doing?" " - The Mentat Handbook - Dune
If all we know is our specialty, we are of little use to others or ourselves, and worst of all we are a draining bore on those around us. There is nothing more sad than a boring Wizard.