Is blocking required in framed walls?
No blocking is not required, but you might be using the wrong term. If what you are calling &quot;blocking&quot; is actually a Fire Stop, then yes it is required in certain circumstances.
Blocking is a term that describes wood flat nailed behind the wall finishes to provide faster support for materials that lay across the face of your wall finishes. It is also one of those terms like &quot;coke&quot; or &quot;soda&quot; or &quot;sheetrock&quot; that is misused as a general class of things when it really refers to a specific thing. The trades will use the term &quot;blocking&quot; to describe framing included in the wall system besides the studs and plates. Often times someone will call something &quot;blocking&quot; which the code classifies as serving some other specific purpose. This is why pictures are so useful to include in questions about &quot;what is this thing&quot;.
I will say this, there are a lot of reasons to install blocking. Fixing twisted framing is very far down on the list; framing serves two main purposes: it holds up the thing above it, and it lets thing hang off the face of it to conceal things running in the space it creates (&quot;the wires/plumbing/bodies behind the wall&quot;). You don't need to fix the twisting to accomplish either of those things, and you don't use blocking to correct &quot;twisting&quot; when it does interfere with either of those things especially right now when the cost of lumber is stupid high and things like furring strips and planers or just whacking it into a different plane with a hammer will make those problems disappear.
That said, fire blocking is a must, and that's laid out by code. If you're asking about fire blocking and you want to know the specific regulations, call your building department (no need to mention your project or your home address or whatever) and ask them to point you to the local adopted codes, then go look up the regulations on fire blocking. Usually every ten feet and full height closing off from slab to joist above so no air can pass behind the wall from block section to blocked section over the wall or under the plate, and from one floor to the next. Fireblocking and Draftstopping will be in the section governing fire stops.
Read this This guy says it better than I can:

The International Building Code (IBC) Section 717 and the International Residential Code (IRC) Sections R302.11 and R302.12 address requirements for concealed combustible spaces. The code requires fireblocking and draftstopping to ensure concealed spaces are not continuous.

It is important to understand the distinct differences between fireblocking and draftstopping set by code. Construction dictionaries and common knowledge do not reflect the code distinctions.