We have continued working on North/South. The kimura is a fairly slick move but it involves letting pressure off your partner. A paper cutter choke is an option where you can stay heavy. Basically, from north/south move one arm between your partner's arm and their body. Reach under their shoulder and grab the back of their collar or shoulder. It can get a bit crowded due to the weight, various limbs, etc. With a good hold, rotate while driving your shoulder into their body. Stay heavy. It should look like your moving into kesa gatame (but with one arm under your opponent). Grab your partner's other shoulder with your free hand and drop your elbow across their throat. The whole thing should happen very quickly.
The paper cutter is a fairly bread and butter technique. I have fallen victim to it many times. While on bottom in side control I've started to bring my inside hand up beside my face to make space. Then I can bridge into my opponent and (hopefully) get to half. Sometimes my partner will give up the cross face and put both of their arms on the outside, prompting me to spin out under their torso... and right into the paper cutter.
I learned a few things drilling the technique. I spent time with S. who really is a gentle giant. His top pressure is tremendous so I feel like my lower ribs have been well tenderized. I also learned that a big guy doesn't really have to go for a technical choke. His paper cutter was really more like some sort of face crank. Regardless, I tapped. With battered ribs and a bruised jaw, I feel like I've been in a real fight!
The submission as a whole happens very fast. There is an interesting momentum change where you think that your partner's hips are going one way and then they reverse. You realize you're caught and you think you can shrimp out but your head is pointing the wrong way.
I also learned a bit about defending the position. Keep your elbows in and your hands up. Flare your elbows and your partner won't be able to get your collar. As for spinning out of side control without getting caught... I just don't know.
As for sparring -- the same lessons. My guard is really poor. That's okay. I'll just spend some more time working mount escapes! While sparring with T. I maintained a tight closed guard. He stood up, slammed me, and was immediately horrified and apologetic! I was completely okay with it. In retrospect, if we was in position to slam I could have swept him. Next time.