Why would you not include all the data? What if the monthly was breaking support or resistance and doing a trend change you cant see that support or resistance on the weekly? You could be going against the trend and not know it.

Spec traders need all the data just like a hedge fund or a commercial would need. That would include quarterly and yearly charts as well. 

Trading is hard enough...it would be even harder for me if I had one hand tied behind my back. it would be like only including 5 years worth of data on a weekly chart.

Spike