Other than distributor rotation etc., does this sequence apply to the six's as well?

 

Yes.

Any engine where the distributor has contact points, or electrickery things.

Once the V12 went Marelli, NO.
The AJ6 onward, NO.

Very old school teaching. The Manual states the specs, but that engine cannot read, so knows nothing of what it is expected to be or do. Every engine has the "sweet spot" and this is how I was taught to find it.