Frank: I am currently using Callaway irons. I love them, but they are about 10 years old now. How often should you update your irons? – Brandon
Brandon, Iron technology has not changed very much when you compare it to the changes that have been made over the last 15-20 years in drivers. Since your irons were introduced, few significant changes have been made to change the overall performance since then.
There is, however, the overriding “Placebo Effect” that comes into play when you buy something new; whether technically better or not, you feel good about the new club, and that feeling gives you confidence. This effect will influence your performance significantly more than the change in technology of the new design.
In its simplest form, an iron is a piece of metal on the end of a stick. This piece of metal has changed in shape over the years to position its center of gravity (c.g.) low and in the center of the face.
Also, the material has been distributed to the perimeter of the head to increase the MOI (forgiveness factor). The c.g. has been moved as far toward the back of the head as possible. The sole has also increased in size to create more bounce and more forgiveness of mistakes. All of these things have been incorporated into the design of irons for at least 10 years or more, with only minor tweaks to the design since then, such as springlike effect in the face which will increase the distance of the iron, but not significantly. After all, if your 7 iron doesn’t go far enough, I suggest you take out your 6 iron.
Bottom line is that there have been many changes, but they’re of small importance when it comes to a performance improvement that we can actually detect. Having said this, we must admit that there is nothing like a brand new set of irons in our bag for a new season. Be careful, however, not to let your old set know that you’re thinking about replacing them, especially if you’ve made good friends of them and they generally do what they are told.
A couple of other points (pro and con) about changing your irons:
1) if you play and practice often, especially on sandy soil, you irons’ grooves are probably worn out. This is most important with the short irons and wedges.
2) you should change your grips as needed, either due to wear or hardening with age….new grips could make you happy with your old sticks.
3) the lofts and shaft lengths on the newest clubs are likely different from your current clubs (longer, with stronger lofts), so you will get different performance. You may: a) have a larger “gap” between your iron set’s highest lofted club and your lowest-lofted wedge; and b) have smaller distance gaps between your longer irons and your hybrid clubs.
Does anyone buy a set of irons anymore? I am 80 years of age, and for the last 15 years or so I only carry an 8 iron, a 9 iron and wedges. Except for my driver and fairway woods the rest are all hybrids. I also find that I may be better off not necessarily using the same make of irons and hybrids.
franklygolf 
I would like you to take this one step further and address changing irons due to age.
This is great advise. I play Hogan CFT’s about 11 years old but only for about 15 nine hole rounds a year. I will wear out long before they will.
A couple of other points (pro and con) about changing your irons:
1) if you play and practice often, especially on sandy soil, you irons’ grooves are probably worn out. This is most important with the short irons and wedges.
2) you should change your grips as needed, either due to wear or hardening with age….new grips could make you happy with your old sticks.
3) the lofts and shaft lengths on the newest clubs are likely different from your current clubs (longer, with stronger lofts), so you will get different performance. You may: a) have a larger “gap” between your iron set’s highest lofted club and your lowest-lofted wedge; and b) have smaller distance gaps between your longer irons and your hybrid clubs.
Does anyone buy a set of irons anymore? I am 80 years of age, and for the last 15 years or so I only carry an 8 iron, a 9 iron and wedges. Except for my driver and fairway woods the rest are all hybrids. I also find that I may be better off not necessarily using the same make of irons and hybrids.