In my opinion, when it comes to weapon training, especially sticks or bladed weapons, it is difficult to tell if anything will 'hold up' if one doesn't train drills with a partner. By this I mean that it is difficult to simulate the 'cocktail' during controlled training (although the kinds of things which have been discussed on the forum about 'reality based training' likely come closest), but a quick way to find out if those moves we have trained with the stick involving twirling or 'fancy' grip changes midway through movements are utilitarian or merely pretty is go at it with some vigor. In the case of stick work, this may mean free sparring or drilling at full speed and power. Personally, when working with live blades, I have no interest in "sparring" per se. However, working with a live blade in a drill situation focusses one's attention remarkably, and, in some ways may simulate something similar to the 'cocktail.' This is not because the intent is necessarily to cut one's partner. Rather, it is simply the fact that I know that intentional or not, if I don't properly receive my partner's technique, I will be cut (but this is perhaps another thread).
My suggestion is to 'simply' test these techniques in progressively more 'realistic' scenarios. It is always tempting, I think to say that movements which look 'fancy' are decorative only. Generalization like this is, I believe, a mistake - certainly it has been for me. In the past, those movements that I have categorized as overly fancy have sometimes later been techniques which I realized I did not understand.
I do think that the idea that small muscle movements degenerate under stress is fairly incontrovertible. Nevertheless, small adjustments in the angle of one's wrist when one is holding a knife make all the difference in the world to the person being cut... I suppose the question always comes back to where each of us draws the line, realizing that this degeneration occurs. Do I (because of the realization that my small muscle control will degenerate), aim a knife slash not for the areas on the arm which I may know will incapacitate the arm, but rather think in terms like "just cut the arm?" Or do I exhaustively train the movments (small muscle movements included) which are necessary to effect my goal (incapacitating the blade arm, in this case), hoping that the degeneration will not lower my capabilities to the point at which they become ineffectual?
Sorry, Cecil. It seems I've got more questions than answers!