In my service desk role we tend to encounter issues that happen regularly enough for me to create us scripts to use. I imagine a sys admin would encounter situations like this 10fold. Essentially scripting makes your job easier and more efficient.
I know of situations where simple things are required in mass volumes and as such a tiny script helps. For example, when we were experiencing some network issues we were asked to perform a series of tasks, copy/paste the output and then submit the output. Doing this as a once off isn't too bad, takes about 20mins but at the time we were getting A LOT of calls. Spending 20mins on each one wasn't viable so I made a simply script that done the commands and output the data into a text file. We ran the scripts remotely through PSEXEC and we got it down to a couple of mins a call.
Another example I remember reading a while ago somewhere was that someone needed to update thousands of documents. It wasn't anything too dramatic, essentially they needed to search and replace a phrase and the script that he put together obviously greatly reduced their time. Scripting in general is also to perform menial tasks automagically. Things like backups, clearing temp files and all that are done behind the scenes.
Lastly, in answer to your question: Both
