WAS THAT A RISE?
Some times you are not sure. If it wasn't do you wait or do you cast. Thing is do you have minutes to spare. Sure you do it's a day out fishing. Waiting often helps because, one, you might see what sort of bug is drifting down the stream to cause that possible rise, and two, the fish may rise again in the minute you waited and give the exact location which then gives you the chance for an accurate cast two feet above the rise ring. You never know the next rise could be the fish eating your fly. All things consider a good out come. However, if it does not happen and you are sure you were accurate do not cast again and change the fly. Smaller usually works but you could be using the wrong size or pattern. In this instance a #12 Miss Knobby X to a #14 Miss Knobby X was no good. I then tried a flying ant pattern, next fly was a #14 Mack Blowie. The fish in front of me ended up eating the Mack Blowie. Well Blowie me down !
Rule of thumb if the fish refuses change the fly.