The coding of expert advisors is always advancing and there is now even software that can read news alerts and adapt that information into a trade. This new wave of programming is the forefront of using fundamental analysis in trading algorithms; there are issues with this that a fundamental trader could point out but that is a conversation for another article. The limitations of a trading system come down to the programmer. There are hundreds of indicators on the market that give direction to the markets and they will be correct a percentage of the time. The problem is making sure they are correct enough of the time to ensure an overall profit at the end of the week, month or year.
It is common place for a Forex robot to work for a period of time then go through bad patches that have the potential to eat up all your profit and even blow your account. Although these Expert Advisors are sold in good intention there is no way of knowing how to accurately predict the market and a trading system based on rules might not fit the market next year as it did the year before.
A Trading System That Can Adapt
In conclusion a Forex trading system that really works is going to be one that can adapt to the trading environment at any given time by using more than one set of rules. Using a system that adapts multiple rules can adapt to multiple scenarios. For Example, a Forex robot that uses a scalping system in a trending market might lose consistently when the market consolidates. Having a system that could detect the change in the market and switch to a consolidation technique would result in exceptional results.
There are hundreds of systems on the market and the best tip we can give to purchasing one is to look at the past results and pay particular attention to the amount of drawdown. A Forex trading system that really works will have a drawdown of less than 20% anything more than this then there is a big danger you will blow your account eventually.