Lincoln Center has members, not subscribers. The distinction is important because membership is different: members can buy tickets for any performance they want from the get-go. Previews tend to be the big sellers for LCT shows because they are cheaper. I've found that tickets are often easier to come by post-opening, especially if a show doesn't receive the best reviews. And even when they do, as @z5 said, they rarely completely sell out. I think the last show at the Newhouse that claimed to be "completely sold out" was Domesticated, and even that had some availability open up as the run progressed.
"You travel alone because other people are only there to remind you how much that hook hurts that we all bit down on. Wait for that one day we can bite free and get back out there in space where we belong, sail back over water, over skies, into space, the hook finally out of our mouths and we wander back out there in space spawning to other planets never to return hurrah to earth and we'll look back and can't even see these lives here anymore. Only the taste of blood to remind us we ever existed. The earth is small. We're gone. We're dead. We're safe."
-John Guare, Landscape of the Body