casting distance varys from venue to venue and species to species. On most beachs flatties can be caught wintin yards of your feet, a little further out bass and coalies, beond the breakers most speices of fish, on some venues long cast are needed to reach rays. When you get to learn to read a beach then you can cast to gutters, depressions and other fish holding features, some may be so close the shock leader knot doesnt leave the reel.
Sometimes distance casting is a big advanage as a sandbar may be offshore or the conditions arent good, ie bright sunshine on a shallow beach, but in these conditions i head to a rock mark, pier or slimiar deep water mark when the fish are at your feet, well about 15 feet below
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At night distance isnt as such a big issue as under the cover of darkness fish tend to come closer to the shore.
so in short distance casting is an extra tool we use to help catch fish, but its double edged as you can cast over the feeding zone and blank, i have put a baited trace 150yards on a field but when fishing i usually cast close then work my way out but find most fish between 30 and 100yards from my feet.
hope that helps and answers some of your questions, if not ask away