well it depends on what your looking for, if im just trying to catch a fish... 30 minutes, but if I feel im in a good spot for a monster I will give it an hour, seems the 6+ footers take a spot over and shakers are rare there, and in turn if your in shakers the odds of a monster drop... not impossible but a big fish is improbable in the nursery..... so just remember good structure where big fellers might be could be a little slow... but sturgeon fishing is that way.. hot or cold... rarely in the middle. as you fish them more you will also notice they turn on and off worse than any other fish I have ever targeted! so diligence is the name of the game and that scent trail theory is ridiculous to me.