There are good methods to improve frames made the conventional way: that is, from 2 by 4s on 16-inch centers. Building Science Corp. found that wrapping the frame of a house with rigid foam insulation increased the overall R-value of the walls and reduced heat loss.
Some builders have switched from 2-by-4 to 2-by-6 construction because it makes deeper stud cavities for thicker insulation. If you’re using fiberglass batt insulation, the nominal R-value jumps from R-13 (R-15 for high-density batts) to R-19 (R-21 for high-density). But spacing 2-by-6 framing on 16-inch instead of 24-inch centers creates structural overkill. Spacing the larger studs farther apart adds room for insulation and decreases thermal bridging.