We treat DF in the same ways as material components. Which means that they are assumed to be available and don't need to be kept track of, except in very rare circumstances or when grappling (however even the latter is often forgotten).
In theory, every divine caster should take very care of his holy symbol jsut as an arcane caster should of his spell component pouch (or spellbook!). But the chance of losing it, having it sundered or stolen, or having problems in manipulating it never comes up in our games. It is a situation that adds very little to the fun of the game, as after the first time it happens the player usually starts bothering about having more foci or pouches in the backpack, sewing them on the clothes, concealing them with a spell, spending a few more money for a special item to protect them, or getting a feat which finally lets you forget about them forever (such as Eschew Materials).
Essentially, it's the kind of thing that gets an implicit agreement from the DM that would not be bothered much, unless maybe once to create the trigger for a whole adventure.
