I agree with previous answers that there is such a thing as perfect.
However, I believe this must exclude professional service providers.
ie; a person must be degree-qualified (ie, 'perfectly' equipped) in order to describe him/herself as, a Practicing Physician, a Practicing Lawyer, a Practicing Psychiatrist, a Practicing Accountant etc etc..
On the face of it, 'practicing' isn't a particularly reassuring descriptor, as you prepare to go under the surgeon's knife, or seek your accountant's help to avoid being eviscerated by the IRS, or whatever.
Presumably though, it's actually a way of saying that professional people understand that standards and 'practices' continually evolve; so they cannot afford to stop learning...
This was a good question, jlastevens. Words are interesting aren't they?