Shooting a lot of line reduces the number of false casts needed to extend the length of your cast. It’s also very beneficial for casting longer distances in general, and for making a long forward cast when you only have enough room behind you for a short back cast. To shoot line well, you must cast a tight loop on the final forward cast, but that forward cast must be preceded by a good back cast with a similarly tight loop. A clean, slick fly line shoots better so make sure your line is in that condition.
Another thing that helps reduce the number of false casts is making your first pickup off the water (or off the ground if you’re practicing) efficiently. Always start with the rod tip very low - nearly touching the ground or the water - and with all the slack removed from the fly line. This way your initial pick-up becomes a good, strong backcast and you’ll have plenty of line speed immediately, which eliminates the need for excessive false casts.
There are other considerations for casting efficiently, some of which also relate to comfort and injury-prevention. Unless you’re making an extremely long cast - beyond 60 feet - your casting hand should not be elevated above head-height when making the cast. This prevents fatigue and shoulder/elbow issues from developing.
Ever watch a good caster and think, “He sure makes that look easy”? When that happens you’re watching somebody cast efficiently.