Under what circumstances is it ethical business practices to ask employees to multi-task or do more than one person's job?

Analyze the following ethical situation using YOUR ethical philosophy. Read the situation and then in your answer, explain why this is an ethical situation, what the "issues" are, and how an "ethical" person would resolve them. Explain how YOUR ethical philosophy has helped you reach a conclusion about how to resolve or analyze this situation.
As a result of the economic down-turn starting in 2008, efficiency has become more and more the byword of the successful business person. The axioms of the efficiency expert are: "Eliminate what need not be done; simplify what must be done; combine tasks wherever possible."
Putting this into practice means, among other things, eliminating people's jobs. Sometimes it also means making one person do two or three people's jobs. As company's gain the upper hand in employment (when the number of employees wanting good jobs is higher than the number of good (i.e. high paying) jobs available), they will more and more expect employees to be willing to work longer hours and to do accomplish more and varied tasks.
1. Under what circumstances is it ethical business practices to ask employees to multi-task or do more than one person's job?
2. Under what circumstances is it ethical for an employee to refuse to do more work than can be taken on in a conventional 40-45 hours per week?
3. Let's assume that it is BECAUSE employees are willing to multi-task and do two or three people's jobs, that others LOSE their jobs. Who is more at fault ethically? The employer who requests the extra work from the remaining employees? Or the employees who are willing to do the extra work, thereby putting the others who aren't willing out of work?
4.How do you feel Aristotle would have solved the above ethical situation differently or the same as you did using your philosophy? Please explain the reasons for the similarities or difference