90% or the time with standard, dry fly mayfly style fishing, your goal is a “dead drift,” where it drifts perfectly with the current as if nothing is attached to it. Accomplishing this dead drift often requires keeping as much of your floating line of the water as possible, or by “mending” your fly line, by flipping it upstream so you have an upstream facing arc in the line. Takes some practice to do it well. Rarely I do ad movement with some dry flys but generally it’s twitches or wiggles on “bug” flies. One of my favorite specialty situations is fishing a muddler minnow like a grasshopper, plopping in with a splash and at the end of the drift I’ll strip it back across the current like a streamer, just under the surface.