In lieu of 3x sole plates, my approach is:
At sole plates bolted to concrete or masonry, specify 3x with 4x as an
At sole plates nailed through plywood diaphragm to floor framing, specify 2x
continuous with 2x blocking between the studs, nailed to the sole plate with
the same number of 10d nails per foot as the total plywood edge nails per
foot on one side; the plywood is nailed each side with half of the edge
nailing into the sole plate, half into the blocking, similar to the way it is
nailed to the top plate, but keeping nails away from blocking ends.