A better concept still is not to overexpose at all, but to key the exposure to the darkest area in which you want texture and detail. This is easy with a spot meter, but most metering systems are too crude, or are biased too heavily to slide and digital exposure (where the important thing is to avoid blowing the highlights), to allow for this -- hence the advice to 'overexpose' when it's really just a question of 'exposing correctly'.
And, as Chris says, you then develop for the highlights, i.e. you keep the contrast low enough (through reduced development) that you get a pleasing print, with a full tonal range, on a middling grade of paper.
Tashi delek,
R.