Whenever you dont like them anymore, or the grooves are absolutely SHOT...i get a full new set every year, but some people have them for 30 years...its all in your preference and your budget....But wedges and stuff get beat and I would reccomend no more than 4 years with wedges.......
Basically whenever you feel like it (and whenever you can clear a hiding spot so your wife doesn't find out ). A good rule of thumb is probably not to buy clubs more than once a year, but that doesn't mean spend $2000 a year on new sticks religiously.
Then, again, you've got guys like Forged who hold onto their clubs for 35+ years with no plans to switch.
Oh, I switched. I just never got rid of my old blades. I gave the cavitybacks a fair shake, matter of fact there is an old thread around here about that. In my opinion the blade is superior club, and the game improvement stuff is mostly hype. That's just me, you guys use what ever makes you comfortable.
Whenever you club manuf. brings in a new model . I've lately been going through a set a year the past 2 years and this is the first full year that I'm still really happy about the irons I have. Hopefully I'll be keeping these for a while since I didn't like the MP-67s as much as I thought I would.
Irons can last you a lifetime, as can putters. Wedges are probably necessary to change every 2 or 3 years, depending on your level of use. Driver is changeable on the drop of a hat!
I change every 2-4 years... that way my clubs are always 2 generations behind the times... LOL
Not that there's anything wrong with that. If the clubs worked fine 2 generations ago, there's no reason why they shouldn't work fine now. Not that we'd ever believe that.
There is a great story I read about Moe Norman -- often cited as being among the most perfect swings in history -- only had 3 sets of irons his entire life. This is a man who would hit several hundred to maybe even a few thousand balls a day. He said he had to replace them when there was a worn spot in the middle of the heads. WIth the softer materials of today, I would imagine that the club faces and grooves would become unusable a little more quickly. But, I would also imagine that you could probably hit 1000 balls a day for 10 years before it would be really noticable. Now, when you want to replace... that is another issue.
My first clubs (and current ones) have lasted since I was 12 years old (7 years ago). I finally ordered new clubs because I was starting to play more and wanted to get some clubs fit for me. I could still go out and use them, but it'll be nice to have a set with my specs.