Unless someone goes to the trouble to test his meter, metering techniques, aperture, and shutter for accuracy, he never really knows for sure his true shooting speed. Therefore, because of the lattitude of color negative films I believe it is best to shoot at some degree of overexposure until such tests are made to prevent underexposure and loss of shadow detail if the shooting errs on that side. Half box speed (one stop over) will probably take care of most errors.