Earlier today we talked about a cellphone user survey that reported that 65.5% of the 400 respondents planned on purchasing the next iPhone model. It goes without saying that this is a very high percentage, and it doesn’t even factor in the people planning on upgrading to devices besides the iPhone. This got me thinking, just how often do people upgrade their devices?

In the good old days, the answer would probably be every two year. You would sign a 2-year contract, get the newest phone, and then two year later you would sign a new 2-year contract and get the newest phone. Rinse and repeat. But now, in the age of super fast technology turnaround, fanboys, and eBay, the average user-device relationship is far more uncertain.

Personally, as much as I’d like to upgrade my phone every year, I stick to the old  two-year upgrade plan. I started my smartphone ownership with the iPhone 3G, then I passed on the 3GS and upgraded to the iPhone 4 when it came out. I’ve been rockin’ the iPhone 4 since it launched, having skipped the iPhone 4S, and now I’m planning to upgrade to the next iPhone whenever it comes out.

More and more frequently, though, it seems like people are factoring in the early termination cost to their smartphone bill as if they’re already planning to pay full price to upgrade device each and every year. I know many people who are in line at the Apple Store every launch day, even though they aren’t due for an upgrade for another twelve months.

And it’s not just iPhones, either. I always thought of a tablet as more of a computer than a smartphone, and as such I figured most people would keep an iPad for a few years before upgrading. But there are many proud Apple customers out there who pride themselves on having owned every iPad model. Now, in the spirit of full disclosure, I upgraded from the iPad 2 to the new iPad after only just one year, but only because of my position at an iOS-centric website. I assure you that, had it not been for professional reasons, I would have happily stuck with my iPad 2 for a few more years.

Now don’t get me wrong, I don’t think there’s anything wrong with frequent device upgrades if you’ve got the money, but I just find the whole thing a bit surprising. Our favorite Apple devices are sturdy and built to last, but many people barely hold on to them for a year.

What is your opinion on this? Are you all for upgrading as quickly and frequently as possible, or do you think customers should really get a good amount of use out of a gadget before opting for the latest model? How often do you upgrade your iDevices? Let me know in the comments section below or on twitter @TiP_Jake.