I am sure you have wondered if you could use a suburito in training or not. Let's see a question I received and my answer to it.
A. I myself used a suburito (suburi-to) in training once when I was a junior high school student. So you can.
However, you must make sure that you ask your training partner for permission if you can use a suburito with him/her.
Plus, do not strike hard.
If you cannot control a suburi-to then I do not want you to use it in training. You will hurt your training partners big time. You can break your partner's wrist or give concussion.
I suggest that you should use a heavier shinai, not suburi-to. A little bit heavier shinai than normal shinai you use in training.
Do a lot of suburi and big strikes over and over. Your shinai will start becoming heavier. I recommend this than using a subirito in training.
Please read the article, "Is it wise to use a subiri-to?" as well.