If you are going to the trouble of opening the wall, blocking horizontally is an inexpensive addition to that job. Studs are cheap. You might as well, sure cannot hurt (I would at least block at the mid-point, min.). I would go 24” o.c, or go ‘whole hog’ and block at 16” o.c. as well.
You will wind-up with a very strong wall, and it will be done.
You will wind-up with a very strong wall, and it will be done.