Here’s the honest answer. It depends. What are your goals with having more than one? Some people carry 2-3 cards because the diversity makes sense. For example, they may have a traditional credit card along with retail store cards (think department store) in order to take advantage of discounts that may only be offered when using one card vs. another. Similarly, some credit cards are more generous with travel perks or cash back awards, and you may end up getting another card to take advantage of those programs while keeping your first card open.
By the way, that is a helpful strategy in building and preserving a strong credit score since length of credit history accounts for about 15% of your overall score.
So, back to our answer. If you’re a savvy shopper and want to take advantage of introductory 0% interest rate offers, or tap into perks that your current card doesn’t offer, we say go for it. As long as you can manage multiple cards and afford to pay off the balances, it could be advantageous. But there is always a delicate dance between the number of open lines on your credit report, and the amount of available credit. Both can be detrimental to your score if over utilized. So if you are going to opt for multiple cards, keep your credit limits low, as appropriate, and ensure you have the income to cover it all.