With all due respect, you might be asking these questions in the wrong place. You (only) have 6 cards, barely a blip on the radar for some of us (perhaps overly) enthusiastic points and miles (and credit card and SUB) mongers. Many of us have 20 or 30 open accounts with multiple sock drawered cards.

If your goal is to simplify your life, then yes by all means get rid of 3 or 4 or 5 cards. If your goal is rebates or cashback or enhanced travel via points and miles then the answer is completely different.