I have learned that all markets have it's own personality, yes they all have chart patterns, but IBM does not trade like DELL even if both deal within same sector. Just like ES does not trade anything like Dow.
When everyone starts, markets are fun and exciting, more markets, more trades, we are taught more is better, not so when trading. If your knowledge and discipline allows you to make profits, eventually trading becomes quite boring, this when you have figured out you have attained a good degree of profiting from your craft.
I now wished I had learned more from the experienced when I was just starting. Instead of looking at more markets and getting more signals, less markets and learning what to do AFTER I got into a trade is much more important. Anyone can get into a trade, but you have to identify what the price is saying for you to profit.
Some instruments do have a limit of size you can push thru without undo slippage, whereas the ES can handle 500 contracts pretty easily, whether you can breath is another thing after entering.