It all depends on how close to the actual, as-built color/texture you want (need) the finished texture to be. If I just need something that is close, oftentimes I can download a suitable color/texture from the SketchUp Texture Club. And even if the color is “off” a bit … if the texture is what I am looking for, oftentimes I can “adjust” the color to align it with my needs.
Also, you might checkout this recent post from @DaveR. He forgot more while having his morning coffee than most of us know. You would do well to use the search feature of the Forum … and pay particular attention to posts by @DaveR.