If you're wearing them once a week then my gut feeling is that every three to four months might be overkill, but you never know. You don't want to saturate them with whatever product you choose to use as it'll make them heavy, greasy and potentially darken the leather. I walk miles in my boots and they only get done at the start of autumn and at the end of winter as a rule, although this isn't set in stone.
Bear in mind, too, that most 'country' boots and shoes will be made from leather that is more water-resistant to standard, 'dress' calf - and will often have been treated with wax as part of the tanning process.
With stuff like Sno-Seal, Chelsea Leather Food and Obenauf's HDLP less is definitely more...
CandJONLINE - are any of your leathers considered to be 'waxy' leathers and if so, which ones please? Do your country calf leathers fall into this category?