Here in Canada there are quite a few R2000 homes. I’ve built walls using 2 X 6 plates with 2 rows of 2 X 4 studs each row at 24" OC. One row is flush to the inside edge of the wall plate and the other row is flush to the outside edge of the wall plate.
Another common strategy is building a double wall using 2 X 4 studs each wall on 16" OC and a space between the 2 walls. The studs on each wall are offset to minimize thermal bridging. Another advantage of this construction is the vapor barrier is on the outside of the inside wall. Both walls and the space contain insulation. In Saskatchewan the space is at least 3 1/2" which satisfies the rule where the vapor barrier can’t be more than 1/3 of the overall wall thickness. Plumbing and electrical are on the inside of the vapor barrier eliminating the need for poly pans etc.