I only did on my F150s if they looked like they needed it. I replaced the brakes every year and a half or so, and they generally were in pretty good shape. I only had to have them turned twice. The first time was when I first changed the brakes on my old '93 and the previous owner wasn't particularly good with maintenance. The second time, I got a set of pads that weren't ground down properly, and there was a hunk of metal that scored my rotor terribly. The store did it for free, and replaced the pads.
Really, if the rotors don't seem scored at all, it may not need it. If it'd serve you purely for peace of mind, you may as well have it done. It's better not to worry about the cost of having something done early rather than worry about having to do it all a second time.
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I fish better with a lit cigar; some people fish better with talent. - Nick Lyons