It depends if you're eating anything else. Managing sugar is less of an issue since snacking as you go is usually possible. Your body is pretty good at telling you went to eat more, but knowing when to supplement salt is less intuitive.

Salt concentrations are tricky too. Saline solution is ~3500mg/L of sodium, but that's over kill for drinking. Since you reabsorb some sodium when you sweat (less if you sweat more), you wouldn't want to replace lost water with an isotonic mixture.