I don't like the traditional leash attachment from the calf to the centre of the surfski. On remounting it typically gets entangled around your leg. If the ski gets violently pulled away from you by wind or wave it's broadside on and it can exert a large force on the leash, the single attachment point and your leg (experienced this in surf in Portugal).

On my Epic surfski (and many other skis) there are four attachment points behind the seat with bungee threaded through them to strap down a day bag or whatever. I've threaded a piece of cord through these with a small stainless steel O ring that's free to slide. I have a Vaikobi 2-Piece Surf Ski Leash. The carabiner clips onto the O ring. The attachment force is now spread between four mounting points and if the ski gets pulled away from you it bears away rather than being broadside on. On remounting the leash is out of the way and doesn't get entangled.