For me I keep it even as much as possible. If I'm creeping along in traffic its mostly front or not at all b/c I'm using my feet for balance, walking the bike etc.
I got my bike with 7111 miles on it (1 year ago yesterday) and am currently sitting at 16924 with probably half the pads left. I have no idea if the original owner had to replace them or not. Few other habits are pulling the clutch in, rolling back on the throttle in advance and easing your way into braking. I've got zero complaints about the brakes on this thing.