Ethernet cables have saved me quite a few times while installing Linux. (But that's irrelevant to apple, they don't even need to concern themselves with drivers.) Besides that I haven't really needed an ethernet cord all that often for my laptop. (Or at all really.)

For my desktop, depending on your definition of "use" (If that means installing an ethernet cable, or connecting to a network with one.) I last used one a few weeks ago, or right now.