The fish aren’t biting.
Well, last night the fish weren't biting at all. It's been over a year since I've gone fishing and not caught at least one or two fish. I was fishing in a new area for me at an odd time. I tried several different lures and varied the presentation. No go. Last Sunday, I pulled a 16" 2lb bass from the same waters. So what was different? Different time of day, different temperatures and slightly different lures.
What can I learn from this? That even though yesterday we used a technique and it paid off big doing the same thing today may not have the same return on investment. We need to be constantly changing, improving adapting. (Different lures and presentations.) And even then we still may not see the return we want. However, giving up isn't an option. If anything the lack of result kept me out longer than I had intended. Maybe the lesson there was cut your losses and get on to something more productive. I keep thinking if I had gone back to a more familiar location I would have at least caught something.
Kind of like Extreme Programming versus Waterfall. Even if you don't get to the target you had hoped you at least have some deliverable for the effort that was put in.