Before I got shodan I used to practice kata by myself all the time.
When I was first learning kata there are a lot of steps to remember and I used to struggle to just get thru the motions, not even starting to dig into the meat of what the kata means.
Rather than wasting sensei's time because I would start on the wrong foot, or would step the wrong way, I used to walk thru the kendokata by myself (both uchidachi and shidachi) twice a week until I had the motions down pat, and incorporating any suggestions I was given.
I don't do this as often now days because I have developed a good muscle memory, but having the basic motions down made it easy for me to adapt to a new aite's timing, as well as easily take new advice or suggestions because I didn?t need to focus much energy on just remembering the steps of the kata.
Kendo-Guide.Com: Thanks for the comment. No need to add anything. It is just like learning how to drive a car. Practice until every movement becomes automatic. Therefore, it is a good idea to practice kata on your own too.