[isatrader]

If it has worked well for you that is explicitly a good reason to not change it.  I've been using 20 day SMAs for a while, I think from Trendavisor, but it is a popular time period.  I formed the impression for recent years that 150 day MA was very slow and 50 day SMA was still quite slow for a trader.  So the 20 day SMA is my 'is it above the 20 day SMA then just leave it alone' test.

I think it all depends on the typical holding period for a stock. i.e. if you are going to hold for less than a month then the 10 or 20 day MAs should capture most of a momentum move from a breakout, whereas if you are looking to hold for multiple months, then the 50 day MA generally contains most strong uptrends with an occasional pullback to it, or even below it for a few days.