Ideally only 1/2 of your accts should show balances, and in terms of cc's the ones that do show balances should be at 1-7% utl.
I don't think it makes a difference in terms of scoring whether you use them and PIF monthly, or don't use them at all so long as you follow the 1/2 showing balances and 1-7% utl. The to use or not to use question usually holds more weight on CLI's and what the issuer likes to see, but I don't think it matters for your score. It should report in good standing even if you don't use it, unless the CCC marks it as inactive.
