I believe 'optimize width' would set the column width according to the values in the field, not the column header. E.g. if Sales Org field (VKORG) if 4 characters then that's the width you'd get in ALV. To get sufficient width for the 'Sales Org' header we'd need to increase the width accordingly.
It works the same way in ALV, OO or not, as far as I know.