Almost every house in the Houston area sits on expansive clay soil. When it rains the clay swells; during a dry August it shrinks. The slab moves a little with it, and the first place that shows is the drywall above doors and windows, where the wall is weakest. A thin diagonal crack there is usually just the house breathing.
The signs worth a closer look are different: cracks wider than a quarter inch, cracks that keep growing, doors that suddenly stick, or cracks in the brick outside. Those can point to foundation movement that needs a foundation company, not a drywall crew. We'll tell you honestly if what we see looks like more than cosmetic settling.
For the normal kind, the repair matters. Spackling over a crack and painting it lasts about one season. A lasting repair means opening the crack slightly, embedding mesh or paper tape, floating it out in two or three thin coats, and then matching the wall's texture, whether that's orange peel, knockdown, or smooth.
Texture matching is the part that separates a good drywall repair from an obvious one. The patch has to disappear under paint, and that means matching the pattern, the depth, and the sheen of the surrounding wall. Do it right and you'll forget where the crack was. That's the standard we hold every repair to.