Define fanatical. It's not that hard to get hyponatermia severe enough to make you sick on a hot ride that lasts several hours. I've experienced it myself once, about 7 hours into the Climb to Kaiser. I felt really bad and had to lie down on the ground for an hour before continuing. I've been on group rides twice where other people have gotten it. The symptoms are debilitating. I hear you can sweat out up to 2 grams of salt per hour -- it doesn't take long at that rate to run through your body's salt stores.

Nowadays, I carry Endurolytes, which are basically fancy salt capsules. They can make the difference between finishing a ride or ending up in the ER.