Given the distinction I just made between reporting and carrying a balance....
The strategy that many of us use is to just use our cards naturally and not worry about utilization or how many cards are reporting a balance. Some months it will only be one card reporting a positive balance, some months it will be all cards. We just set up all our cards with autopay (to PIF whatever was on the last statement) and then we get on with life and forget about it.
Not everybody does that, but many of us do. As long as you can see that (based on your own credit limits and spending patterns) such an approach will keep every card at < 49% individual utilization and your total utilization at < 29%, such a strategy works fine.
The logic behind it is that if a person's goal is to gradually build credit over time, then the extra scoring points a person gets from AZEO (All zero except one) and for having hyperlow utilization -- well, they are nice, but you can get those basically any time you want by adopting AZEO in the month before an important credit pull. AZEO does not help you gradually build a score. Do it if you like, but don't do it because you think it will help you in the long term.
The responses you have gotten so far focus chiefly on how AZEO affects your FICO score.
There's a separate issue which is how your individual creditors might view a card that is almost never used. That's not a FICO issue. That involves its internal policies. Your initial post decribes a person who might have 8 cards but use 1 of them for almost everything. You could find credit limits lowered because you almost never use a card, and indeed have the card cancelled if the card goes for long enough without being used.
So be sure regardless to use each one of your cards at least every six months -- unless they are store cards, in which case you can likely get away with far less frequent use. Also be sure to activate each new card that you get and use it for something small fairly soon after you get it. Unused cards can be cancelled far sooner than ones that have been used at least once.
