I think such a consistent return can be achieved by algorithmic scalping - numerous trades, day and night, a few pips per trade.
You do realise that 15-20% per month is an abnormally high return, compounded it makes around 700% yearly. And with abnormally high return, comes abnormally high risk!!!
I am personally experimenting with such algoes of my own on M1 timeframe. Instead of using SL, I employ automatic grid-trading to get the position out on profit. However, grid is a dangerous animal where sideways market can ruin you fast, and I have to admit I had to stop my algo once and recover manually.