A risk-to-reward ratio in isolation is irrelevant. If it weren't, the best bet would be playing the lottery.
What makes more sense is profit factor = (average win * win percentage) / (average loss * loss percentage). An equivalent formula for profit factor is gross profit / gross loss.
Imagine a PF of 2.0 which is really good. You can achieve it with:
1. $300 avg win, $100 avg loss, 40% winners
2. $200 avg win, $100 avg loss, 50% winners
3. $100 avg win, $200 avg loss, 80% winners
On this information, all three strategies are equally good. To discern more, additional metrics like Sharpe/Sortino are needed.
Some intuition for profit factor:
- a PF of 1.0 is break-even
- a PF of X means that on average, you make X dollars for every $1 you lose