The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
Never make the same cast twice in the exact same way. It didn't work the first time, so what makes you think it will the second?
In fact, nymphing presents so many more subtleties and possibilities than dry-fly fishing that it is the dry-fly fishing I often find mechanical and uninteresting.
A second unconvincing presentation to a feeding fish will do more harm than good.
I believe what Shawn says about changing weight to present a different look or action, I'm too lazy or forgetful to do this as often as I should. Experimenting with and changing weight frequently is a suggestion Joe Humphreys makes in almost every one of his books or videos on nymphing
I would counter, however, that if you're making a half-dozen casts to a rising fish to try to match his timing, then you probably shouldn't have made the first five, instead opting to watch the fish for a few minutes before making one really good cast to him.
In fact, nymphing presents so many more subtleties and possibilities than dry-fly fishing that it is the dry-fly fishing I often find mechanical and uninteresting.
Dry fly fishing has charms I can't resist
I'm not sure I'd characterize us as "thieves" exactly. (Though you're probably right that many dry-fly "purists" might see us that way.)
you are luring your prey briefly out of his own world and into yours.
I love the Quality Control on this board