It is- but you are just doing this for fun. On sim you get all the excitement for FREE!
ES is my primary market but I'm focusing on oil right now as there is a lot of volatility and I've always wanted to trade it and ES has been rather stale.
If I were wanting to learn I would take the sim opportunity to focus on the days structure and taking 1 or 2 trades after, say, the first 30 minutes has passed. I would pay attention to what I see unfold after I took a trade but not care about stopping out or reversing- solely trade directionally based on days structure and be an observer of the market, my emotions and what it's going to take in the future to let a trade hit my target or know when my thesis has been blown. This excercise could very well benefit from having two markets to watch as you will get more experience and you won't be focusing so much on trading anyway.