When trading, you aim to play optimally; mind, body and soul.
A loss of income in this manner over a period of time can reinforce negative psychology. When this happens, you start second guessing your target price (and second guessing in this game mostly has negative results). This is not because you're not decently good at it, but more because your faith in your ability has diminished due to previous results.
I have tried having defined targets and would stick to them and then I have tried to allow myself a little "dancing" space. If I get a $0.23 move and my target was $0.25, I'll take the $0.23 as opposed to having it trail back and take me out at $0.15. I just lost $0.08 for the sake of gaining $0.02! Statistically, that strategy is flawed.
With trying both methods for extensive periods of time. The result in the post above shows that being a little flexible has a better outcome in the long run.
The same principles have worked well with me on entries.