Training on your is good. Maybe on the best but close to it.
(#1 - With an instructor
#2 - With a group of educated practitioners
#3 - With good reliable education material
#4 - Solo flight; doing what it looks like they are doing)
Still, let's say you have either one or more of the top three and you just want to do some added training at home when you are not studying at the dojo/club/tapes. Then training on your own can be very helpful.
For example, practicing moves at home for a test.
Doing some stealth training by seeking up on people/creatures (can be dangerous!).
Percision techniques like play darts, hitting ball/or something tyed in the air with your weapon/fist/leg, etc.
Endurance training.
Strength training.
Stamina training.
Etc, etc, etc.
Training on your own is great but a whole lot more fun with a buddy.
