Personally, I have headcovers on everything including my irons and wedges. I started doing this back years ago when I was single because I didn't like the sound of the irons clanking together when I walked. Added bonus, now that I'm married my bag always looks the same no matter what clubs might have recently been added. :angel:
I get the "no iron headcover" thoughts. However, what does make me cringe is watching wedges bouncing off of someone's putter as they fly by in their cart.
When I first started playing about 15 years ago (and actually had a decent swing), I was paired with an octogenarian gentleman. His bag contained all woods except for the SW and putter. He kicked our collective asses. So as many as necessary to get the job done. I currently have 3, but flirting with a 4th.
I use fourteen when my clubs are traveling or in my car. When on the course covers are only on driver, 3 wood, hybrid and putter. Iron covers stay in the car. Nothing against Iron covers but prefer not while actually playing.
As many as you want. Its your bag and theyre your clubs. For me, there should be as many headcovers as their are woods and hybrids, as well as one for the putter. For me, thats 6: driver, wood, 3 hybrids and putter.