1. Straight-line rod tip path. The tip travels as close to a straight line as possible through the stroke, so the fly leg is straight and the loop narrow. Unchanged from 30 to 50 ft: it results from the other four.
2. The casting arc matches the bend in the rod. The arc — the angle change of the rod butt during the stroke — depends on how far the rod bends, not on line length by itself. At 50 ft, with similar line speed, more line mass bends the rod further, so the arc widens to keep the tip path straight — widen it because the bend increased, not because the cast got longer.
3. Proper force, applied smoothly. More line needs more force, or the same force applied over a longer distance; lengthen the stroke rather than overpowering the cast.
4. Slack line kept to an absolute minimum. Start every stroke with the line as straight as you can; at 50 ft slack costs more, because there is more line to straighten.
5. The pause matches the time the loop needs to straighten. More line outside the tip unrolls more slowly at equal speed, so the 50 ft pause is usually longer than the 30 ft one; faster line needs a shorter pause. Distance alone does not set it.

Alongside the five, keep the line and the intended rod tip path aligned with the target — the 180-degree principle — and be ready to say whether you would haul at 50 ft; Task 21 permits it.

Source

From the CI Study Guide (2025) (PDF) — the Five Essentials and Task 21; terms from the FFI Fly Casting Definitions.