The other time when you should cancell some cards is when you have TOO MANY cards. I think anything over three cards, you are not only putting yourself in financial risk but Potential lenders look at that as a potential RED FLAG that this person could get into some serious financial problems quickly.
If you have, let's say 6 cc each, for easy math sake, with a $10,000 limit on each. Future lenders can look at that as a possible $60,0000 potential debt. Not good
Don't let anyone tell you that having alot of cards is good for your score, it's not. Your only obligation should be your financial welfare to yourself and your family not the ALMIGHT FICO score.
If you have alot of cards close some the newers ones and keep your older ones. I personally recommend anyone who is kinda of struggling but not there yet, to have no more than two cards. That's all you need to keep a nice credit history going. Too many cards = Too much debt.