How many credit cards should i have?

I currently have 4 cards with $2k limit on each card 1 store credit card for use only with the store. And 3 regular cards.. Amex, discover it, Wells Fargo.. There all cash back rewards. I want a sky miles with Amex. Should I apply or no. I travel 1 time a year, but also want to increase my credit limit on all cards

?2016-03-28T21:34:59Z

I have no objection to how many you have; but is the Amex sky miles worth it? {Often not, if there is an annual fee.} ... Travel one time a year ... NOT WORTH IT