A solid foundation is key to a balanced and powerful swing. If you are too narrow, balance will be jeopardized.
If you are too wide, you will restrict your movement throughout your swing. The shaft is the longest, so it makes sense that your stance should be widest with this club.
A base that is too narrow does not provide enough stability to support a driver swing. I see this more often than a stance that is too wide.
This is overkill. A stance that is too wide restricts your turn and downswing movement to your finish.
STANCE FOR POWER!
Ideally, a slightly wider than shoulder-width stance sets us up for good balance. For your mid-irons, your stance should be slightly narrower, and with your shorter irons even narrower.
The stance becomes narrower as the clubs become shorter.
The stance becomes even narrower as shorter irons require less rotation, such as wedge shots, chips, and pitching.