Mike,
Many of us that have been training prospectors and miners over the years focus more out of the water than in the active water channels. Starting with Bench Deposits (where the water used to be) to Residual Deposits (where the gold is coming from off of a load) and ultimately the lode. While teaching that not all gold comes from something as simple as quartz veins on the side of mountain.
While Detecting, I will very seldom is ever work a stream bed unless I can see the bedrock and can see from the surrounding areas that larger gold may have made it to that point. I'll focus on Bench deposits and work my way up.
Doc and I have had a running Joke for years but is is a true fact that every gold nugget we find we have a discussion with. "Het buddy where'd you come from, got some family and friends laying around as well?" You would be surprised how much you can learn from a nugget on finding more nuggets. Every speck of dirt, quartz, iron staining is a story. the fun is in finding the pages that make a book.