How many hours per day is the right amount for a Supply Chain/Logistics manager to be effective:- 8 hrs ,10 hrs, 12 hrs or more? is a 5 day wk enough?

8-10 hrs -5 days a week is enough

In normal circumstances, competent well selected staff should effectively perform a well designed business plan within the normal company working hours. There may be exceptional unplanned situations which may require extra hours to accomplish, but this is the exception and not the rule.