"undo" really can replace "redo"

["niDapeng"<steveneo@21cn.com>]

I know Emacs use "killing-ring" concept to cicle undo, and 'redo' operation is implicitly done under this cicle. But, is it really good way? 
When I set killing-ring size enough large, the "redo" is turing very boring when I miss the correct position of ring. 
For instance, if my current killing-ring size is 200, I try to undo last the 40th step operation, but, unfortunately, I undo 41 times. At this case, I have 2 choices, one is keep undoing until the cycle is back(so boring, and I have to very careful to prevent next mistake). Another way, is I manually to mend the 41th operation(maybe type some text again). 

Hi, Emacs gurus, my "redo" concept is correctly? I have to be familiar such operation? Certainly, I know there is redo.el available for this. But why emacs doesn't take "redo" as default package?


Thanks
Dapeng



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