How many hours per day is the right amount for a Logistics operator to be effective:- 8 hrs , 10 hrs, 12 hrs or more? is a 5 day week enough?

depends on what they company does and what they need and need it when, yet the operator is a human so more time mean mistakes, so if it will be a long time better to have more than one and shifts 

Depends on the type of Job and operational requirement. But always work and life balance is required to get max output from human being----is the most important I think.

Depends on operation. When you have more materials you need more time or more employees accordingly

24 hours