In the beginning it's better to have 1 credit card and pay that down properly as you use it to help build up your credit and then venture on to 3 credit cards and after that you can have more if you can afford them.
However for most people 3 credit cards is enough and more than 3 credit cards could hurt your credit if you get to where you cannot pay off the credit cards properly.
Having more than 3 credit cards is too many credit cards for most people as you may not be able to keep up with the payments and it could hurt your credit.
There's not really such a thing has having too many credit cards.
However you could have too many credit cards that you cannot pay off which can hurt your credit.
Generally it's a good idea to only have 3 credit cards and use them responsibly and pay them off on time to help build your credit.
If you have more credit cards and use them without being able pay them off then that can lower your credit score.
Having accounts open with a credit card company will not hurt your credit score, but having zero balances will not prove to lenders that you are creditworthy and will repay a loan.
Lenders want to make sure you repay, and that you will also pay interest.
There is no ideal number of credit cards you can own.
You can own as many credit cards as you want as long as you are eligible for it.
However, having multiple line of credit can make you look like a desperate borrower and increases the overall available credit.