I will write elsewhere about my personal reasons for trying to cast better, a purposeful pursuit that is happily without end. In this piece I will concentrate on practical benefits. As ever these are just my thoughts and experience. Not instructing or proselytising.
Catch more fish with more accurate presentations

Distance as a Dimension

To me distance is not an end in itself, ego stroking aside. In fact, casting too far is often worse than landing too short because of the danger of spooking fish. Distance then, is simply one dimension of accuracy. Imagine your target is a 12″/30cm diameter circle (a dinner plate) resting on a tape measure. Hitting it on the near to far line is just as important as on the left to right line.

Accuracy and Target Selection

If you do a lot of sight fishing, and by that I mean casting to fish you can see and watch you soon realise that there are different target areas for different fish in different conditions and in different moods. Sometimes you need to put it almost literally on their nose and other times anything closer than several meters is likely to spook them.

Knowing where to put the fly in different scenarios is not the subject here but trust me it varies a lot and sight fishing is the key that unlocks a lot of essential information about where to land the fly for a competent cover. Having used your knowledge to choose the target, you need to hit it (obvious) and preferably at the first attempt (not always obvious). Sight fishing also demonstrates that the chances of a take diminish with the number of presentations, not infallibly but as a good rule of thumb. There are plenty of times when your first shot is the only one the fish will allow you.

Expand the Kill Zone

Not my most subtle subject heading but I struggle to think of a better one. I hunt fish and though I kill very few of them I still hunt them. If we were talking about deer instead of fish it would make perfect sense and sensibility to say don’t shoot at an animal you aren’t confident of killing cleanly. In my fly fishing it refers to the area within which I can confidently, competently and easily cover a fish or, to mingle metaphors, take the shot.

Not very long ago, say as recently as two years, my kill zone was roughly 10-20m or 30′-60′. Of course I have caught plenty of fish closer in and further out but that was the preferred range. One of my reasons for improving my casting is to expand the zone out to 28m or 90′ and to do that I set myself the goal of casting a 5wt outfit with reasonable accuracy out to 30m or 100 feet. (More on that elsewhere.) The reasoning is simple. If I can reliably hit a 30-60cm target at that range then ten to twenty percent closer than that should be straightforward. Put another way, at whatever range your casting accuracy begins to hit the wall, twenty percent closer should be a doddle.

Waste Less Fish

The fish we catch are usually classified into a large taxonomy of success but the fish we miss, strangely, have fewer categories of failure. “He didn’t want it”, “Wrong fly” “Poor cast”, “Bugger, lined him.” These about cover the field but how about the fish I wasted? I mean the ones that were catchable with a competent presentation but a series of casts got nowhere and as if by magic or divine intervention, the fish disappeared. Nope, very often this was a fish wasted by the angler. I hate doing that. When I get a chance I like to make the most of it. More chances mean more fish to hand. Better casting means more chances and fewer wasted fish.

Fish Better with Longer Leaders

We wouldn’t fish long leaders to small fish in tight water but as a general rule fishing longer leaders catches more fish, especially in impoundments. Why? Because the fly line lands further away from the fish and is less likely to reduce their enthusiasm for the take.

How long? Well for me and over time the standard leader for a floating line has grown from 9-12′ (3-4m) to 15-18′ (4-5m). Of course, sometimes I go shorter and other times longer.

Longer leaders require good line speed to turn them over. Higher line speed requires a better and more efficient casting stroke rather than more effort in casting.
Fish Better with More Confidence and Less Frustration

Enough said. If you’ve had a meltdown you know what I mean. If you haven’t had one, stayed tuned.