Just had an experience a few days ago. I had leak while riding. I used the pressurized puncture sealant. It slowed the leak down, but did not stop it. I arrived home, pumped up the tire a bit and left it over night. It lost half the pressure. I removed the tube and found the foam had escaped through the puncture yet, had not sealed it (very small puncture). Patched it, and now wondering, how reliable are sealants?