for eg.: RSI is best fit for a sideway market, while MA is more suitable for a trending market...
For MA,,I believe no matter which ever time period you are using, as long as the market is trending, u will make money if your direction is correct and following your own defined rules.
For RSI, I am sure you will be well returned if you short when RSI >70 and long when RSI<30, Provided the market is sideway(rectangle movement)...
So my personal feeling is that every indicator has its own best suited market working condition and limitation.
I have tried to use RSI for each market conditions. sideway market is fairly easy to apply RSI. however, if the market is trending, either up or down, my experience is that: in a bull market, I will only long when RSI is low and divergent, rather than seeking short when RSI is high and divergent; and in a bear market, I will only short when RSI is high and devengent, rather than seeking long when RSI is low and divergent.
so the most critical question for me is what kink of market movement it is now and going to be next------ up, down or horizontal?