All it does is-
Help with top end stability.
Help relaunching super fast when you have worked it out.
Kill the power and land consistanty down wind where an out of control kite ends up.
Kills the power so well full power tricks you arent punishished by the kite.
Good systems work well for depower/relaunch with over 15 twists in the lines.
Safety leash can be connected all the time and have reliable performance.
5th connected Safety leash is the only practical leash for riding sliders.
Your kite can be landed directly down wind on tight side shore beaches.
Your kite turns off completely doesnt tangle up the lines and can be relaunched after release.
Your kite lasts longer as it doesnt get stressed from speeding in the water
You can set up the kite to drift of the wind while wave riding.
When released in the surf theres more of a chance the kite wil float lightly up and over white water. Instead of catching the white water and blowing panels out.
5th is like a extra hand on the kite so you have more control of the wing when its down, meaning you can handle it in difficult situations while still controlling the kite at the bar.
5th also helps you in a situation where you dont want the kite to fly at all, No tight sweeping lines across the wind window.
2 tangled 5 line kites is not too bad when the rigs are released.
5 lines Russian starts in almost no wind, 3 knts, Cause you can decrease the angle of attack so far it will fly.
If your system has a cleat you can cleat off 30cm and you wont fly when raving sh1t on the beach to your mates.
5 lines is generally a 100% depowering leash that will less likely break due to stress damage.
More skilled riders use 5 lines, cause they can...Geez does more than I thought.