Ridgeback,
I guess you're right in regards to the definition of things. I guess in principle we are on the same page.
I tend to define these based on their objectives and goals more than anything else. I also try to be pragmatic and practical in regards to how I define things as well.
I personally feel everything has a place and purpose in the grand scheme of things. So-called "dead" movement drills have a basic function and purpose in my opinion.
It develops coordination which is probably the most important quality or attribute for proficiency in any sport or physical activity, which Bjj is. Alot of people who complain or have issues about their skills and progress don't realize their problem might stem directly from poor coordination.
Coordination, as you probably know, is the ability to "integate" all the powers and capacities of an individual into an effective act of "doing". In other words coordination is essentially perfoming a movement or a series of movements in a smooth and graceful manner.
A person who lacks coordination will always find themselves on the short end of the stick. They will never find the correct spacing or distance, their timing will also be off, their rhythm, their reaction will always be slow, they will alway telegraph their intentions, and they will always suffer from "braking" because they have excessive tension in their movements. They suffer from a lack of control over their own bodies.
The best way to develop coordination ia through precision practice which is what so called "dead" drilling is.
So-called "dead" drilling is all about moving your body correctly, positioning you limbs in the correct place and doing every thing together as a whole. It is about controlling your own msucles and making them do what you want them to do. Developing coordination is a matter of training the nervous system and not just training the muscles.
Everything I do in terms of executing technique, reaction, timing, and rhythm as they relate to tecnhiqes is ALWAYS better when I excessively (that is do alot of) so called dead drilling. I find that so called dead drilling increase my coordination which directly effects everything else.
So-called dead drilling not only is excellent for introducing you to a new movement pattern it is also an excellent means of "correcting" and "maintaining" that movement pattern. People tend to forget that things deteriorate over time, and these things include ones physical skills. Mistakes always creep into ones techniques no matter how technical and experience one may be. This is why so-called dead drilling is good because it prevents those mistakes from becoming too big to handle over time. Why do you think basketball players constantly work on their jump shots (and other basketball skill) in a way that many, in the martial art world, would consider "dead" drilling? I ultimately makes a difference in their form and helps to maintain their technique. You know the more jumpers a basketball player takes and makes in practice the higher his field -goal percentage increase. Incidently in case you didin't know filed goal percentage is the amount of shots a player makes in an actual game.
Anyway I consider so called dead drilling to be a very important drilling activity to do. The so call "live" drilling is also important but like I said anything has a function and place and "live" drilling has a place right next to so-called "dead drilling.