Re: final lock doesn't work
In general, I've found that they work best when applied while standing, and maintained throughout until the final tap. But most people won't like the pain that goes with that, and I couldn't practice that way all the time. BJJ/judo style locks and pins seem to be a bit different in that it's easier to go from control to severe control to break in easy gradients. Aikido pins seem too often to go from loose control to break or dislocate really fast...sometimes without much in between.
Even ikkajo/ikkyo pin...just hold down the arm above the elbow and pick up on the wrist. I've known dislocations to occur very quickly that way. Whether or not that is *good* aikido is another question...