This varies from individual to individual and from organisation to organisation. I had set a norm that by the first siren of the factory (6.45 am and the shift starts at 7.00 am) to be inside the factory premises. Unless the boss sets example, he has no right to expect compliance by others. There has been earlier discussion on this topic, of sales and marketing people being exception to the general rule. There could be many reasons, in deed most middle level and senior executives work very late in the evenings and that is the justification claimed for coming late, in Marketing/Sales the most often heard alibi is that there won't be customers available early morning but would be at work near the close of the shift hours . There are too many well known business heads who had made a personal habit of arriving before time (like JRD Tata, E Sridharan, V. Krishnamurthy, Amul Kurien etc). These days there are flexitime, work from home etc rigidity regarding timeliness and punctuality have to be strictly viewed from the organisational perspective. But let us not forget the age old adage that timeliness is next to godliness.