Surfing Waves

Just had a O&E XT leash break in pretty benign conditions. Also had the Creatures of Leisure Reliance break a while ago too.

When should I replace them? How many stretches might I count?

Have a look where they are breaking and what the break looks like. small fin cuts and abrasions and flexion cracks can often be seen around the area where the break occurred.
Around the swivel and into the end parts that mount to the ankle wrap or the rail saver are often an area that breaks when the heat weld cracks.
Good practice is to inspect the leash before the surf!,
One this is guaranteed , when you don’t want it to break it will!

As Jaffa said, always good to inspect before you surf. Also wash it with fresh water after you use it and if possible keep it stored straightened instead of rolled (that's more so it doesn't start entangling in you during surf).

Still, be ready to swim out of the water if it breaks, because even with all that care it's possible it will. If conditions are too heavy for you that you don't think you can get out of water safely without your board than it's probably a wise decision to surf another break that has weaker conditions.

I used to work at Town & Country Surf shops as their Surf Buyer and handled customer warranty complaints. In my entire time there, I've only seen one leash that actually "snapped", all the rest were fin cuts. If you can post a photo of the ends were the leash broke, I can try to figure out what happened to it.

( if you got an iPhone 13 Pro, you can get a really close up shot )