Yeah, he was not trained and it has been made clear through the episodes I have seen that Ichigo is very inexperienced on a lot of things. So ripping yourself out of your own body probably takes a little concentration. It is something that I would imagine that Ichigo does not have figured out. He is more about the muscle and overwhelming strength than being smart and refined. He is still very rough around the edges and just all raw power that is slowly becoming controlled. I would imagine if he practiced it he could get out of his body, but it is usually an emergency that he has. So I doubt concentrating for him would be the first thing that he would do.

He is pretty scattered brained at times too. He cannot remember names I think and forgot that Soul Reaper spirit ribbons are red. There were other things, but that is what I can recall at the moment. Ichigo is smart in a battle, usually, but that is about where his intelligence seems to end. Though he is surprisingly good in school and taking tests. But even in battle Ichigo is not always intelligence.

Cutting the chain accelerates the process. But that one spirit already had lost his chain. He was starting to develop a hole in his chest, that is representative of becoming a hollow. Rukia said that it would be months before the tear was completely open. Death would be the same as cutting your chain though. And that guy already had lost his chain completely. But with Ichigo the last link in the chain meant that he was going to become a hollow pretty much immediately. The chain eating itself is accelerated I guess, but I don't know. I just do not see the tear being accelerated. It was completely skipped in Ichigo's case. Chain gone he started the transformation on the spot. Still seems a little strange.

I don't know I guess unnatural causes outside of death the results in the chain being cut accelerates it. Even though death of the body cuts the chain all the same. I guess that works, but seems a little wierd to me. And there as a girl that I thought only had one link, but was still a long way from being in pain and everything. I don't know just seems like there is a lot of inconsistency.