I learned a lot this in competitive programming. I used to write code that were 3-5x the size of the intended solution. There are many reason why you could write a worse/bigger solution but sometimes when I compared both solutions one thing I could notice is that I could remove a lot of things from my solution until nothing could be removed anymore and the final solution would really seem like it were the essence of the problem.

But even if the intended solution seemed simpler, it could be much harder to discover it.