I've been practicing cutting kihon-toho on three goza (now that I have a stand of my own). A couple of weeks ago, at the tameshigiri outside the dojo, I didn't quite get the first part of the cut, the kesa-giri. The ironic thing is that I find doing the "harder" cuts of kiriage or suihei much easier than the kesa giri.
As it stands now I can get all three cuts, just not serially as they should be in kihon-toho. Actually, I should say, I'm getting closer to what I used to be able to do several years ago--skill only lasts as long as you practice. As always, to be considered proficient in a sequence you should be able to perform it without error most of the time. What "most" means here isn't specific, but on average you only fail perhaps one out of five or ten times.
Back to my kesa-giri on three problem. You just don't see the same kind of issues with a single goza as multiple. Part of it is in the swing in terms of how wide your swing is, and how long your sword stays in the proper angle as you go through more and more goza.
For me, with kesa, my swing was tapering out towards the end. If I had to describe it, it starts more vertical and ends up more horizontal. Part of it is in how my wrist rotated: right-hand was flattening out. If I drew a curve it starts with a steep curve, then starts getting shallower (math/physics geeks: a hyperbola). What I needed was to try to keep it straight as much as possible.
With my cut on two-goza it wasn't easy to tell since I start much more vertically. But with the flatter angle needed for three goza, the flatenning out became more pronounced. So yesterday, on the cut, I tried to avoid flattening out but rotating my right wrist (top hand) tto the right to counteract.
The cut went through so easily, that there was no stress on my wrist at all. The stress test is one way of telling if you are doing it right. The less stress means that more that impact stress is transferring and diffusing up your arm, rather than torquing and hurting your wrist.
This kind of fine detail is hard to describe without showing directly, and even then not until you try something similar. And then again, this may be something just specific to my own swing and not many others. So I'm not sure if this helps you any other than allow me to ramble on. None of my students have tried three yet, so I can't tell.
Kesa-giri aside, the feel of the other cuts are very different on three, particularly if you trying to get good cuts (the right shape/angle for kiriage and suihei). For us, you're not really cutting three goza until you can get all of those cuts proficiently.
More practice for me I guess