It's worth pointing out that (unless I am mistaken) there are no FICO negative reason statements that refer to being penalized for having too many revolving accounts showing a balance. Just "too many accounts" which seemingly could include installment accounts as well.
Back in April of this year, I pulled all my scores and received negative reason codes of having too many accounts with balances -- and yet I had exactly 2 cards out of 12 showing a positive balance (17%). I did, however, have 2 open loans with a positive balance as well (and thus four accounts showing a balance).
A hyperfocus on revolving accounts only and on the percentage (rather than also considering the total integer number of accounts with a balance) may therefore be a mistake.
Aside from the (possible) scoring advantage of five cards over three, there is a practical long-term advantage, in the that no-annual-fee major cards can be kept open (usually) forever, and thus are a good way to develop a solid thick profile (minimum of six accounts) including several very old open accounts (which protect against AAoA drops and also enable you to maintain a profile in which < 25% of your accounts were opened in the last year).
I say that such credit cards can usually be kept open forever. But it's always possible for a CC issuer to close your card. Maybe down the road a CC issuer will deem you not profitable (as well it should, if you are paying in full and keeping spending low) and close your card. Maybe the CC issuer will go out of business. Whatever. When you have 5+ cards, you are far less vulnerable to having one closed than you would be if you had only 3.
