Your overall utilization should never exceed 30% or 10 as some say. Having balances on too many of your cards can also effect your score negatively. I have been using this stategy and it has worked for me. I have one card with a high utlization (52%) due to a large purchase. I pay this one off at 300.00/mo. I have a cash back card that I use for day to day purchases and PIF every month. The rest of my cards, until they make me a better offer are used for occassional purchases every few months just to make sure they are actively reporting. I rotate which one to use. Awesome since I can now buy gas at Sam's Club using my Walmart card. I drive a small card so it keeps that occasional purchase to under 20.00.
Even though you may PIF every month it doesn't mean that's the balance being reported to the bureau. Some cards report balances as of EOM. For example, yur payment is due on the 7th onf the month, you pay it off. Between the 7th and the 30th you use 50% of your limit. If you have a card that reports EOM, it will report the 50% utilization as opposed to your sterling PIF history. I generally know which cards report when so I make a min payment on the statement date and then pay the rest off right before the reporting date. If I goof, at least I got the min in but so far its been working
