@Brian: aikido is a martial art. one of my reason learning martial arts is to be able to defend myself effectively (aside from the fact that I love learning them) when I had to get involved in a fight. I think one opening can decide the result of the fight.. what's the purpose of doing a technique that you know won't work just to change to another technique?
My responses are coming across a bit on the negative side, so I apologize for that, that's not my intention.
But please understand that sometimes an instructor assumes that his students are on the same page as him, and sometimes doesn't fully explain what's he's teaching because he doesn't want to waste precious class time lecturing on what he feels is already understood.
I also have issues when teaching henka waza. It's hard to convey to students why they must let up on uke during the technique. But if they don't, then there's no reason to transition to another technique. I hate having to teach poor/sloppy/loose techniques, but that's pretty much necessary to really get the gist of henka waza.
I also understand that you believe that you'll execute the 1st technique correctly to end the confrontation, so there will be no need to switch to another technique. But you should reconsider this belief, things can get really ugly outside the dojo! These henka waza drills might save your neck one day.