I suppose the answer to this question is that it depends where you buy your Factory-made wheels.

I build my own but found that it was cheaper to buy Factory-made wheels with my components of choice than buy the components separately. I bought two pairs from Rose bikes, a German firm, and found that although perfectly true, there were a few spokes which varied too much in tension and all tensions had to be brought up to the proper level. Again, the wheels had not been de-stressed which is obviously of great importance when avoiding spoke breakages. Now having said all that, the wheels have remained true and are pretty tough. The front wheel of one belonging to a friend hit a pothole deep enough to puncture the tube and damage the tyre yet the rim deviated by less than a millimetre.