This is always difficult as everyone is different. Usually, once I feel I have learnt everything about my current role, I tend to get bored. Very bored. It’s a strange feeling though because I simultaneously love the fact that I know the job so well. I love how automatic it becomes.
This conflicting feeling can often be confusing but I tend to take it as a sign that I need to study, seek a promotion or a new job with greater responsibility. But (just as a treat to myself) I wait six months or so, enjoying the comforting feeling I get when I know a job so well, hahaha.
If you are feeling restless why not look at your options in terms of rising up the ladder? Or, if you have no desire to progress further, enjoy!