In normal market condition it is fine.
But if the world has a terrorist attack, bomb blast somewhere, or some news comes from china that hits global badly, or another bank is US becomes the victim of recession, and market hits the circuit, This safe startegy will turn into disaster.
Such events don't come by informing us. And one such event is good enough to take away months /years or earning or maybe throw us out of trading.
Risk management and position sizing is crux here when dealing with such unlimited risk strategy. So please do read / think about them as well.
Happy and safe trading