I alway wear jerseys, unless it's a utility ride/shopping, and then I might wear a tech t shirt or some other top that has lycra that is more fashionable. I have long sleeve, short sleeve, and sleeveless jerseys, but over the years, I have found that I wear less of the short sleeved ones and use the long sleeved ones in the beginning of the season or cold riding and that once it's hot out, I like sleeveless. I also have a few different thickness of thermal linings in the LS jerseys. Basically, I now only buy Terry and Voler jerseys, as they fit me the way I like.
I could go for 10 days (or more, if the weather changed) without having to do laundry with jerseys, but I basically keep my stuff until I notice they are pilling, etc. The last few years, I've been better about going through my collection and throwing out ones that don't have the right fit, are pilled, or damaged in some other way. The styles and way jerseys are made have changed a lot in 15 years, and while I had a couple of jerseys I liked from 2002, they were too short and had other features I didn't really like.