Finally worked it out. The first point to absorb is that it only affects bones whereas objects have their keyframes dropped into the Non Linear Animation Editor (NLA). This was very confusing for me at the start but eventually it became apparent that the action editor creates timelines that can be arranged and blended in the NLA so one has to be very aware of which “strip” is active when moving things around (with autokeyframing on) as keyframes can end up in the wrong strip which then produces unexplected results. This method seems powerful, for example the entire first scene with the btterfly flying and gliding was very little detail animation. I animated a 5 keyframe strip of the wings flapping, 2 keyframe strip of wings in a gliding position, and that’s it for the wing movements – the variations were created by blending in and out of duplicates of these strips set at different playback speeds. So when the 2 frame glide strip is blended over a flap the wings ease into that gliding position, but because I only keyed the main bones in the wings the flickering tips aren’t affected and so continue to flicker. The walk up the stalk was of course animated all the wa though.