I would not focus to much on terminology like side-wing etc. I don't think there is an official definition of what a side wing is. You can start the cut anywhere at the mandible border and basically move the segment(s) in every direction (forward, back, outwards) - the question is if it makes sense and if its safe enough. So its best do discuss this with the surgeon.
This is correct. I would add that the border of the chin is part of the mandibular border. Also, the BASIC segment is one that cuts through the chin all the way back to the gonial angles. I say basic segment because that's the one someone should familiarize themselves with first if they expect any explanation as to cuts through the basic segment as to what can be done with different cuts in secondary surgery. I've included a simple chinwing diagram that shows the basic segment. As to when it's not safe to cut all the way through from front to back (as illustrated in the diagram), it's when the jaw bone is too steep and or the nerve would be too close to the cut. As to a second procedure, if the first one was safe, the second one would tend to be also because they go through the SAME cut. However, I tend to think that risks could go up if they have to remove prior bone grafts. If no removal of bone grafts,the secondary procedure is one like you mentioned prior. The release the (whole) segment (via the prior cut they made to release the first time). A vertical cut is made to part of the segment which allows them to put the jaw angle back where it was (and also flare it out for more definition prominence). From there, they fill in the vacant space between the moved jaw angle part and the rest of the segment. They fill in with a graft from the hip area. I agree, safety and risks should be discussed with the surgeon. However, safety is different aesthetic effect or aesthetic preference. If a patient was incapable of expressing to the doctor such things as; 'more flare, articulation to the back jaw angles' or making clear what he was aiming for, it wouldn't matter how 'safe' the surgery was.
About the initial surgery (my theory could be wrong): If they would not cut all the way through the back of the jaw angles they would most likely be limited with vertical movement of the segment and correction of asymmetry (depending on the case!!). But if you only get forward movement then i guess it is more possible not to cut all the way back through the angles.
But I think even when the cut does not go through the angle but stops a little bit before the angles the face still can get a bit more round. Take a look at dr.bruscos instagram/imgur page. Look at the female patients there and look at the cut and the outcome. I would like to hear what other users think about that. Sometimes the asymmetry is really noticeable in the after photos.
Your theory is CORRECT. If they didn't cut all the way through the back jaw angle and just left it there, they would not be able to do what you are saying. I would add that if they didn't cut all the way back through the jaw angles and just left them there where they were and just moved the rest of the segment forward, the back jaw angles would not look the same RELATIVE to the forward displacement of the rest of the segment. That's because the mandible gets wider and wider the further back you go. So they are moving a WIDER width more forward which will increase the width of the FRONTAL face (usually a desired goal of the CW). However, if the back jaw angle is LEFT BEHIND, a WIDER width to the front of the face would result in the back jaw angle looking more NARROW via RELATIVE COMPARISON. That's why I think a good thing to move the WHOLE basic segment and not leave the jaw angle area behind. Could even explain what you're seeing in Brusco's photos when jaw angle is left behind, a type of roundness to frontal face. (Only when the patient's jaw is too steep and/or the nerve too close to the cut for safety do they have to leave the posterior part of the mandible where it is.
.......
Again: For only 4mm horizontal movement I think movement of the whole mandible border is not a good solution. It would be so interesting to see before/after because you say that you got very blunted angles from just 4mm. ......
Not sure I would agree entirely with that part. For example, the CW is a good solution for someone wanting some additional movements that can be done during the first CW, like 'dropping down' the border for more facial height or wanting more WIDTH to the front of the face which one can get with even a 4mm advance of the basic segment. However, it's not a good solution for someone wanting only an isolated genio or someone just landing in the doctor's office who's done no basic research, not even looking at a basic diagram before hand of the cut made and the segment it creates where to most people it would be OBVIOUS that part of the back jaw angles would be changing their position with the advancement of the segment. As to blunting with a small 4mm movement of the whole segment, the perception of blunting would still be there if they left the jaw angle area behind for reasons I stated above. width is being transferred forward. So, if the back angles are left behind, a wider width than that of prior would also make the jaw angles look blunted by relative comparison.