True, it's different from tennis, and at higher levels of play nobody should have any GLARING weaknesses, but I think a thread covered this topic a few weeks ago pretty thoroughly (about playing the table and/or the opponent) and most folks seemed to think -- it depends on the situation.
As for me, Jude, hey, I love offense, I spend most of my practice time running out. These days I hang in there with the 6 ball ghost, which ain't world-beating, for sure. My defense has only recently begun to catch up (I was losing too many matches because I was sloppy in that department), and I think that's where most games are won and lost ... winning that early or mid-game safety battle (or at least not selling out) SO that you get the best chance to run out.
3-foul wins really are rare for me ... last night was unprecedented, and I just take it as a sign that I'm making some progress in safety play, that's all.