If your pool is clear, your FC and CC are fine, you don't keep having drastic chlorine drops, then the detritus in your filter is past rotting and you needn't worry about it.
Backwash when the pressure goes up. If it's once a week or once a month, so be it.

However, if you DO get an infested sand filter (very rare, but I know someone who had one) it's cheaper and easier to just replace the sand. At $5 for 50 # it's not pricey.