Like for movering average cross over systems, does anyone know if they have a shelf life? Or if they just go on forever doing the same thing?
Well I guess mechanically speaking they just go on doing the same thing because they are nothing more than mathematical equations. However, the results these equations produce are dependent on the input data they use. Markets move in very different ways at different times depending on the underlying economic fundamentals, sentiment, uncertainty, speculation and so on. This is generally called volatility. The results of an MA cross-over system will vary according to these changes in market activity and generally perform best in longer-term trends. When markets are ranging these MA systems tend to whipsaw.
I don’t think you can talk of a “shelf-life”, rather they may need re-optimising if the overall nature of the market price movements change over a longer period of time. Perhaps a dramatic example of this would be if the values of two previously free-floating currencies in a pair were to be linked together in a tight range by their respective central banks.
They always work 50/50, unless you make some corrections and improvements in it. What I certainly don’t use is most tools and indies from techy analysis.