I wipe them a coupe times a year with rubbing alcohol and a paper towel. I also keep my windshield clean and apply rain-x. I think a lot of times people prematurely replace wipers because of streaking that is caused by road grime and oils that accumulate on both of them.
I've got a set of Bosch blades that are 6 yrs old and still look and work great. I've got another set of Peak blades that are almost 3 yrs that work pretty good, but were cheaper than the Boschs and will be getting replaced soon. Not because of poor performance, but because the paint has faded rather badly. I now see where the money was saved during the manufacturing between the two.
For some reason, I tend to have to replace my rear wipers much more frequently than the two for the windshield. I'm lucky to get two yrs out of those before they tear.