If you know how to patch a wall correctly it will not be exposed even years later. Any hole bigger than the size of a dime, I always fill with a hard plaster all the way until the last 1/16th of an inch or so. Then fill the rest with Light Weight spackle, sand, and paint. If you don't have the paint, chip off a piece and get a match made. When you paint it don't just paint where you patched. You want to paint usually 1 square foot, do it with a bunch of very thin coats, and feather out the edges. There is absolutely nothing wrong with making holes as lond as they are drilled or cut neatly and patched right. We work in old brownstone buildings in Boston thet were built in the 17 and 1800's very frequently, and this is usually the only way to go. You think it's bad to do on a drywall and plaster wall? Try it on one of those Brownstone's horsehair and lathe walls. It takes a long time to know how to patch those walls properly.