Of the good fishermen I know, one thing I see in all of them is how easily they can reach conclusions about fish habits. They have a knack for knowing what to trust and when to trust it.
The damned thing about a river is that it changes every day, and the habits of trout follow. If you’re observant enough to see the dynamics of a river, you can predict how the fish will respond, just by correlating their behavior patterns with the changes in water level, clarity, food availability, etc. Often, though, that’s a big leap to take. And it requires trusting in your observations enough to act decisively on them . . .