I'm really surprised at the amount of people who go long times between. I'm curious: when you do spend on bike stuff, do you buy a lot at once and then it all wears out at the same time?

Every month or two, I make routine purchases in the $5-$60 range, covering misc parts, chain lube etc., and find that as soon as I have one thing the way I like it, a consumable runs out or a part I'd replaced a couple years back needs to get replaced again. I guess I'm a tinkerer, as opposed to a "set up once and enjoy" kind of rider.

Big purchases are more in the multi-year ranges. While I've bought 3 new bikes in the last 8 years (one for me, two for my wife), I don't think I'll be buying another one for 5-10 years, and major gear purchases are really unusual. Only one occasion comes to mind, when I went on my first longer-than-a-weekend tour, I spent around $1500 on gear for my wife and I...new clothes, new saddle, new handlebar bag (with insert for organising my dSLR camera parts), new panniers, new pedals... the list goes on. That was 4 years ago, and I still use all those things. Might buy a few more clothes this year for another tour, but we'll see. I don't use them for regular riding around town, so they last a long time.