Well, the term N-Bagger contains more information if there is a time unit attached to it. This has nothing to do with ones personal trading strategies, or trading system, or whatever, rather it will be a more meaningful term to use for discussions.
To me its more clear when someone says stock XYZ is a 10 bagger/year rather than XYZ is 10 bagger (by when?)
As to the PhD thing...Its in theoretical neuroscience and machine learning.
Cheers!
-- Doc J