How often should a person check their credit card statement to make sure that they don't fall victim to a wrong charge or cc fraud?
You are not "required" to check at all, except for the physical statement you receive each month. (Or online if you opted for paperless). That's when the clock starts for you to report fraudulent charges.
That said, if you tend to use a high percent of the card's credit line, you should probably check more frequently, if only to avoid hitting the limit.
Note, the card might offer a feature that alerts you, via email or text, if a charge is made with the card not present. When I charge something via phone or on line, I get an instant alert for these transactions. This might help put your mind at ease.
At the very least, you should look over each statement each month as you receive it. You technically have an unlimited amount of time to dispute fraudulent transactions, but you have $0 liability if you do so within two billing cycles. For other disputes, you have 60 days (which would be roughly equivalent to two billing cycles anyway).
Valuepenguin.com has some more info, and the following chart:
Although, if you are running a monthly budget (which you should be...) it would be better to look over all transactions, credit card and otherwise, at least a couple times a month. That way you know exactly where your money is going and will spot problems even sooner.