In Koryu arts, any ancient martial art from Japan that pre-dates the Meiji restoration in Japan in 1868, the training is done a bit differently than in the Gendai systems, or modern schools of marital art and sport fighting. Don Roley wrote a great blog post about this and goes into detail about the purpose of this type of training. I'll post the link at the end for further reading.
Essentially, the training is broken down into a methodical, systematic way of training combative techniques without actually hurting or killing someone. Essentially, as Done says in his blog post, if you are doing combative training and someone doesn't die, then it is simulated combat. We start out training very slow, giving students a chance to feel out a technique and to ensure it is being done properly. Then, later in a student's training and development, we speed things up and give the feeling and intention more indicative of real conflict. Various training tools are used at different stages of training for both unarmed and weapons training. If you come to a class, you will likely be training slow and controlled. As is often said by my own Sensei: "If you can't do it slow, you can't do it at all." There is also a mantra in martial arts that goes something like this: "Slow is controlled, controlled is smooth, smooth is fast."
Read Don's Blog here for his view point on this and further insights from his experiences living and training in Japan for over a decade: http://www.coloradospringsninjutsu.com/Ranting_and_Ravings_2016/Entries/2017/5/23_Understanding_Koryu_training.html