Adding a system becomes too much depends on you, your routine, capacity, and various other things.
For adding a new system, you must execute your current system smoothly, mistake-free, with confidence, and without stress. If you’re feeling stressed and anxious about the level of activity that you have to do each day, and you add another system that adds more activity on the same days, this is important, as the existing systems, you’re going to start making mistakes because your stress levels will rise.
However, if you have a whole bunch of long systems, and they’re in the market during a bull market, and when you add a short system that’s only in the market during a hammering bear market, you’re not adding much activity. Therefore, you’re not contributing to increased stress levels and mistakes.
Thus, you need to think about what you add and how will that affect your daily routine and your ability to follow the rules consistently. First, if you’re going to add a system and cause mistakes everywhere, that’s going to be a big problem, which is not worth the diversification. However, if you can add some systems without ruining your routine and without making mistakes, then think about the market system map and think about where you are making money, losing money and where you’ve got nothing and add the system that will give you the best improvement in your ability to make money over a range of market conditions.