I've had Bosch Icons on the front for 2 years and 3 months (26,000 miles) and I'm just getting ready to replace them.
I have a few streaks and I think it is due to nicking them with an ice scraper. Otherwise, it looks like there would be at least 3 more months of use on them.
2013 535i - ED, Oct 2012 | Cashmere Silver | Oyster/Black Nappa Anthracite | ZCW | Sirius | Air Blue 80
2008 X3 | Monaco | Sand/Black Light Poplar | ZAP | ZPP | ZCW | Xenon | Rear Fog
1988 Grand Wagoneer | Burgundy | Ghost Flames | 360 ci | Holley carb
BMW CCA #422951