@kdm31091 wrote:
How many is best is a question that is obviously subjective, but if you mean for score purposes, 2 or 3 cards is enough to demonstrate responsible use and keep util relatively down. You can achieve a great score even with 2 cards. You don't want just one because if you ever use it more than a bit, your util is super high, but there is also no need to have 10 accounts (score wise).
Now if you mean on a practical living side, everyone has a different opinion. I don't want to manage 10-20 accounts via spreadsheet or try to eek out every possible penny of rewards all the time because to me it's overwhelming and chasing very small differences in gains. Many do it though and swear by it. To me on the practical side, exceeding 5-6 cards is overkill unless you want to spend lots of time maximizing rewards for each purpose, transferring points, spending for this bonus, blah blah blah, it can get tedious. If you use one card for general spend the majority of the time, such as Quicksilver or Double Cash, you'll get plenty of rewards and you won't get a headache. You can supplement with a good grocery or gas card; whatever you spend a lot on. Just my two cents.
For general spend, this is sort of true. You can do (made up figure warning) say 60% of the gains by sticking to one card (e.g EDP, CSP, SPG, Diners, DC) partly because on many cards the high bonus levels are capped, so maxing out Discover IT gives you $300, whereas DC would give you $120, but would do better on the remaining spend.
But the real gains are in things that some (including KDM) don't like, getting bonuses and MS, both of which will dwarf normal spending rewards. For bonus chasing, you of course need to get several cards over time
