I started trimming in college, about 8~9 years ago. I have a lot of body hair in general, and it just got way too sweaty & pungent as the pubic hair grew. I decided to start trimming & tried shaving; I didn't see much benefit beyond just trimming, so I gave up shaving.
I've been trimming pretty consistently ever since, although I find the time in between trimmings increases if I'm not actively dating (interestingly enough...lol). Never really thought about doing the same with my other body hair, although I might take measures if I continue to get more & more back hair.