I don't think getting a new bow every year has anything to do with needing it. It's just what some people "want" to do. If anyone can shoot a bow to death in one year they should consider a different brand. A new string every 2-3 years is all you need, if you take care of it.
I mean NO disrespect to anyone on these forums, at all. If you take care of something, there really is no need to get something new that often. That's just my opinion. Sure SOME of the bows do make some leaps and bounds, everything does with the technology we have available (examples listed above). In reality, it's an investment. Re-investing your stocks yearly isn't a good idea. Whenever I speak, it's from a financial aspect. So I apologize if I'm biased that way. If people want to do it, great. Do it, but I don't think it'll help you harvest more deer. Be smart with your money, do the research first, then once you purchase something, take care of it, not the obsessive/drive your partner away obsessive. Trust me, that doesn't work out so well. That's a whole different topic though.
I guess the way I look at it is that I get new line for my fishing rod. I don't get a new fishing rod every so many years, I replace the line on it though. Just like a bow, I replace the string on it every few years. It shoots deer, my rod catches fish. A new fishing rod won't put me in a situation to catch more fish, just like a new bow won't put me in a new location to find more deer, or to cover my scent. Regardless of how often anyone decides to get a new bow, if you don't shoot it enough you won't be familiar with it. Just like shooting a shotgun and patterning it for Upland Birds. Or driving your truck in the snow, or driving your boat. Like I said, I mean no disrespect. I just don't think it's justifiable to purchase one as often as some of the people are mentioning.
Edit: Not everyone has 400-600 bucks to drop on a new bow (Hoyt especially) that often. If you stick with a bow that has a good reputation, you'll be happy, and satisfied for a decade. I might be pushing the limits on my bow, but I've taken good care of it and it has taken great care of me. Just like a good dog.