You need to use all your resources as efficiently and efficiently as possible. This means that you must automate whenever you can and use people only for tasks that cannot be automated. It also means that you need to think carefully about what you can automate and about circumstances where only one person will do; and about simplifying the processes you choose to automate to eliminate wasteful or inefficient steps.
You should always optimize your work BEFORE automating it, as automating something that is inefficient or ineffective can result in you doing the wrong thing faster!