Many leashes that are produced have a carabiner at either end. This is very useful to allow easy attachment to the flag out line at your bar, but the harness end rarely requires removal and could snag a line if you became tangled after a wipe out. Worse still, a snag at this end will mean you cannot detach from the kite!
I have mistakenly managed to attach my leash the wrong way around, with the final release at the bar end. Easy to do at the start of the season when you are in a hurry to get on the water. Luckily another kiter noticed my mistake and corrected it for me. If I had used my primary safety and flagged out my kite, my final safety would have been out of reach up towards the kite.
It may require a little work, but attaching the harness end with a loop of Dyneema line made with a Brummell Lock-Splice will prevent line snags and ensure that you can't connect it back to front.
Now that the leash is attached in the safest manner, for most of us it becomes overly long and dangles around our knees when we kite. It is only there to link your harness to the kite's flag out system. Any extra length is required only when performing unhooked tricks and holding the bar at arms length; so as not to partially activate the flag out line.