We usually try to spend most of our time in middle conditions instead of living on the edge of cliffs. When you're on the edge, any fluctuation might send you over the edge. When you are in a more moderate condition, you have some room for fluctuation without necessarily falling off the edge of the world.
This condition of being so close to the edge that you have no slack for choice - that condition is called kuzushi.
Kuzushi is the first phase of a throw in either judo or aikido. You can think about kuzishi in different ways...
- catch uke standing on the edge of the universe,
- put uke on the edge of the universe,
- help him up to the edge of the universe,
- or at least refuse to help keep him away from the edge of the universe.
Doing more than just positioning uke at the edge of the cliff is not kuzushi - it is kake (the momentary effort of throwing), and it is often doing too much. If you push/pull too hard to try to throw uke off the cliff then you can end up moving him past the edge to a position of greater choice/stability. I think a lot of folks (maybe all of us) get too wrapped up and invested in kake - we want to smash and destroy! HARD, FAST, HULK SMASH!
Try getting some practice at positioning uke right at the edge of the cliff - the point of no return - and letting him live there for a moment without trying to push him over the edge. I think you'll find that your tsukuri becomes easier and your kake is often near effortless if you are able to begin your throwing action from the edge of the universe.
We see this sort of action in junokata and gonokata, but this is also a great mode in which to play nagenokata.