Our heroine moves expertly through the forest. Something catches her eye. It's a drop of blood.
But because this is a movie--and we need the audience to know what's going on--it's not just a tiny drop hidden in a crevice. It's a puddle of blood.
And then another, and another.
Puddle of Blood (sorry, I had to fake an image because I don't have a still from the movie)
The blood is so obvious, anyone casually strolling through the woods would instantly notice it. You certainly wouldn't need to be an expert hunter like Katniss Everdeen. But that doesn't bother the audience. Why? Because the obvious puddles, and the ridiculous amount of blood loss associated with them, isn't the point of these shots. The point is that our character is following a trail of blood. And we need to know that.
A simple suspension of disbelief to see what's going on is far more important than any kind of accuracy of what would or would not constitute a trail of blood in the real world.
Film is a visual media, so the audience needs to be able to see what's going on. As filmmakers, we need to remember that the important elements in a scene need to be obvious to the audience, however ridiculous they may appear on set.
Your Media Production Mentor