It obviously depends. It mostly depends the total time you will spend performing the task manually before the system will be decommissioned.
It takes time to automate a task. If you spend more time implementing the automating than you will save when it is automated, you loose time and money. If you automate something and it takes less time to implement the automation than you will spend doing it manually, you save time and money.
Use the calculator below to calculate how much time you will spend doing a task manually. It will give you a starting point when you motivate the decision to automate it.
And remember, automation doesn't just save you time. It reduces the risk for manual errors and increases therefore quality.